Hi MDV,
Good to hear you're thinking of a move to the dark side!
In my opinion the factors to dwell on are:
Scale length: what is the longest you can still play on? Can you tune down low enough (with appropriate string gauges) to retain sufficient tension and therefore clarity?
Fanned Frets: In order to achieve a playable string tension at your selected scale length on the bass side, you may struggle with strings for the treble side - very high tension/breaking/uncomfortable to play. Shortening the scale length for the treble strings is a great way to combat this, while still allowing you that beautiful piano-like clean and great articulation for the bass strings.
As you know, the way Wez built my fanned fret guitar was with the perpendicular point at the 7th fret. This means that for the vast majority of what you're playing, the fingers really don't notice the fanning of the frets. I can't stress enough how playable the guitar is. I literally forgot that the strings were fanned when I picked it up for the first time, because I was so struck with the quality and feel of the natural wood finish, and it wasn't until Wez pointed out that it didn't take me long to adjust that I twigged "Hang on a minute... oh yeah!".
Naturally, I was worried about it before, having not played a fanned fret guitar previously, but there was absolutely no basis for that worry, and I'd urge everyone to get their mitts on a multiscale guitar! The benefits for me are absolutely clear:
Previously, on my 25.5" Ibby in A-E-A-D-F#-B with 13-65 strings:
Flappy bass strings (in comparison), tension was not too bad, but could have been better.
Tuning issues: Not with the guitar (which held tune very well), but with the strings. Hit a string hard, and you'd get a considerably higher pitched note which would come down to the correct pitch over the course of 0.5-1 second or so. Bad!
Now, on my Voiferator with 14-70 (I think it's 70, might be 68...) in same tuning:
Proper tension on all strings, gives really nice feel to the instrument, and means that *all* strings hold the true note at all times, provides very clear, bell/piano-like cleans, and great articulation for the fast (especially low) stuff.
As for the most important factors in tightness:
Amp (flabby amp will never be tight!)
Player (gotta have the fingers!)
Scale length (assuming appropriate choice of string gauge)
Pickups (I'm assuming BKP here ;))
Woods
That's the order I would put them in. The choice of wood should really be governed by the tone you want to achieve, rather than the articulation. I went for Maple/Bubinga/Wenge neck-through with Bubinga wings and ebony fretboard to give a good amount of mid-range bite, plenty of attack, and a blistering bottom-end response. It definitely worked! And that's with a Black Dog in the bridge, which isn't the world's tightest pickup, but does allow the sound to be very open (again, dependent on amp channel, Channel 1/crunch of the 5150-II is quite open, the gain channel is really compressed).
Hope this helps,
Roo