That's a well put together post :D
Sounds like you know the answers but aren't sure which way to jump.
I can see the logic of 4, moving it on (if you can square away the sentimental side, obviously). But from the other stuff you've written, I think you would eventually regret shifting it - it sounds like you've got reasonably wide tastes in music, and I think that further down the line you will need a guitar that does the job that this one does. If it's a good 52RI, they are highly regarded as "the guitar" if you're after that particular type of tele, and there are countless "wish I'd never sold mine" posts on places like the TDPRI forum.
Teles are funny things. It took me years to really "get" them. They never seemed to sound as good as I thought they should. And they can seem, like you say, somewhat harder to play. And I go through moods regarding them - I've got three nice-ish ones, and I haven't touched them in months because I'm in a "bass, strats, and SG" mood. But I know that when I get one of them out it's going to be great again.
I'm kind of leaning towards 3 is what you should do - play the thing. It will eventually really expand your musical horizons and playing skills. When you finally get a tele playing how you were expecting it to sound you find that your playing on other guitars has REALLY improved.
But, I think you need to change your attitude towards it. Don't ever look at a guitar as something you've got to do justice to :lol: - no matter how special or expensive the world says it is, it's a plank of wood with some metal and plastic on it. It's a tool to serve its owner, and you're the owner... whatever you do with it justifies it.
I think a lot of us fall into this "my guitar is better than me" thinking at some time or another (er... I'm naturally arrogant enough, though, that I only really had the problem for about 2 months nearly forty years ago :lol:). Master this and you'll progress faster towards finding out what you and a tele can do.
Regarding 2 - output from the guitar - I've found this can seem a big problem if you've got used to humbuckers/distortion/etc. I'm on strats with singles mainly, I only dip my toe into humbuckers occasionally, but I still grew up making more distorted strat tones, and moving to a tele gave me some of the same problems. There's a few of things I'd suggest:
a) A tele is very responsive to touch (well, any guitar is, but the tele seems to exhibit it more at first) - so it feels like getting a "consistent tone" is easier said than done. Instead of regarding it as a hurdle to get over, embrace the "inconsistencies" - experiment with using them in your playing. I think this is one of the reasons diehard tele players love them so much, it's very easy to make the thing sound different depending on how you hit it.
b) Use the controls. It all depends how your amp is running, but in general, turning the tone down on the guitar tends to "fatten" a single coil, especially a tele bridge pickup. For raunchy chords, I have my tone on about 5 or 6. Another trick some people use is having the tone open, but use the volume as a "tone" control. I've experimented with it, and yes it does work, but it depends on your amp and the music you're trying to play at the time.
c) If you haven't done it already - mess with the pickup heights. Any pickups, cheap or expensive (and I believe the ones on a 52RI are pretty good) change their character with height adjustments. And again, on a tele, because of its apparent sensitivity, little changes can turn it into a different instrument. If you don't know about this yet, it's vaguely "closer to the strings equals more and thicker output, further from the strings is less and brighter output". Some people want the first, some people the second, neither is "right". Also, a "modern" post-early-60s tele wiring (the switch gives you bridge, bridge+neck in parallel, neck, the tone is a master tone working on all positions) can give this amazing middle position tone, but it takes quite a bit of fiddling with the respective heights and angles of the bridge and neck pickup to get it just where you like it.
d) Which leads me to the last bit on output - I believe the 52RI comes with 50s wiring installed and a kit to convert it to 60s. I can't remember what 50s is exactly, but I understand that it can make some of the positions unusable to many players, and I don't think you get that magical (to me) bridge+neck. How is yours wired at the moment? - that might be worth considering. Another thing, which might help your situation actually, is consider installing a four-way switch instead. This is "modern" with the switch giving you an extra bridge+neck in series. This fourth position gives you something akin to a humbucker - it just adds the two pickups together. I suspect that you might quite like this at the moment. All my teles have it, I don't use it much because I'm a home player/recorder now and I have other guitars to do the job, but if I was playing live I would definitely use it.
Finally - the frets. I'm having vaguely the same problem myself. I can actually cope with big frets, little frets, different fret board radius, scale length, etc... But I have one guitar where the little frets are worrying me. It's one of my strats, a Crafted In Japan "62", it was my favourite strat but I've got two Roadworns now. With the slightly thicker and much taller frets these guys just sing in my hands. When I switch back to the CIJ, I have a bit of a struggle to "feel good" on it until I've been playing for half an hour or so.
With my teles, two have tiddly vintage frets and one, a Baja, I took to Felineguitars and had Jonathan put HUGE frets on it. I got it done because I was wearing out the stock frets very quickly, it felt like replacing was a good idea financially (rather than regular dresses and then a refret in a couple of years). The stock ones on a Baja are not tiny by any means, but when Jonathan offered me various fretwires for feel, I went for the biggest. That one plays like a dream for me now - whenever I put it on, regardless of what I was playing immediately before, I just play it, no time needed to adjust.
You can get used to the frets on the 52RI, it is just practice, but it will affect how you play. It might be you don't want your technique to go in that direction? It's up to you. Personally I'd rather embrace the differences and learn to play whatever I've got. But there does come a time when you don't play one of your favourites because it takes half an hour to "get into it" - that's what I've got on my CIJ strat, and I think I'm going to get it refretted. I won't go for the huge ones this time, I'll probably match what I've got on my RW strats - that's well comfy for me on a 7.25" radius fretboard.
I suspect you could well do with bigger frets, it could easily transform your impression of how well you play it. But it's a tough decision to make if the others aren't wearing. It's not cheap, and on a finished maple fretboard, it's quite likely to mean refinishing the board, so even more expensive (it depends how it looks when the old frets have been extracted - possibly "not good" if the neck was lacquered after the frets were put on, which is a standard construction method).
I hope that helps a bit. I went to the trouble partly cos I'm waiting for the gas-man :lol:, but mainly because it sounds like you love this guitar and think you're not worthy of her. I also think you're going to want what a tele does for you eventually, and a 52RI is a monster of a tele if it's a good one.
Gas man's here! woohoo :D
Good luck...
