Well, as I have that exact combination in a PRS SE Custom 24 and I have been singing its praises for quite some time, I really should step up to the plate on this one.
Versatility
I think this is a relative question to be honest because the obvious qualification is 'Compared to what?'. As contemporary pickups go it is certainly a versatile option and I think that's because it's not massively extreme in any particular direction. It has aggression in it but that is tempered by the inherent smoothness of the pickup. It has lots of mids but they're pretty evenly spread so you cut through the mix without sounding hairy or angry. Notes are thick but they're not really fat and while it has a bottom end, you'd never call it a 'bassy' pickup. It's also tight and articulate but it's a hell of a long way from being tight in the 'djent' sense. The tonal characteristics of the pickup do place it firmly in the 80s Metal category and that is where it is most comfortable without a shadow of a doubt but as long as you accept it will always retain these core characteristics, you can take it in other directions. Add an overdrive and compressor as I often do and it thickens up further and can be used for things like Metallica and Children of Bodom but wind down the gain and compression and it will do a very credible Classic Rock sound, albeit with that 80s twist. It wouldn't be my first choice for Blues. Having said all of that, although it's versatile within the confines of most contemporary pickups, there are ultimately more versatile options out there, though I can't think of too many.
In many respects the same can be said of the Emerald. Even though it's in the 'Vintage Hot' section, it is a modern pickup. The alnico IV magnet gives it its sweetness and an incredibly harmonically rich tone but the modern wire gives it all the cut of a modern pickup like the Cold Sweat. I think that's why I like it so much because I feel like I'm getting the best of both worlds and it really is unique. With most pickups in the range, especially neck pickups, there is always an alternative that is similar but the Emerald neck stands completely alone. There is simply nothing else like it in the range. This does make it quite versatile as the modern cut it has means it's great for shreddy styles but the expressiveness you get with the AIV magnet means it's a pickup with a lot of soul. It will do all the styles of the Holydiver with ease but also take you closer to Blues styles. It's a lovely pickup for more modern Blues Rock.
Gary Moore
This is a REALLY tricky one. Gary Moore is my favourite guitarist without a doubt but in his lifetime he covered an awfully wide range of styles. The Holydiver will certainly do some of his material but I'd say it would be most at home around the time of his 'Corridors of Power' album. The Emerald has a bigger operating window for Gary Moore as it will cover that era too but also do a number of his Blues Rock numbers. I can only speak for myself but I'd use the Holydiver/Emerald combo for some Gary Moore songs while for others I'd rather use the Crawler/Holydiver combo I have in my other PRS. For others who want a more authentically Blues tone, the Abraxas or Mule neck would be a better option but I just find the more vintage pickups to be too rounded in the bass for my tastes.
Cleans
Are there bridge pickups with better cleans than the Holydiver? Yes, absolutely, but I don't think you'll find many of them in the contemporary section. The Crawler is the only one that leaps to mind. Move out of the contemporary section and you may find better cleans but then you're starting to compare apples and pears. The main role of a Holydiver bridge is never going to be cleans but with that minor caveat I'd say the cleans are good. The cleans on the Emerald are very good. It's thick and very harmonically rich. I find the Emerald very satisfying to play clean. In some respects my Holydiver neck has better cleans but they're nothing like as complex as those on the Emerald. It's just a REALLY good pickup.
Holydiver compared to the Crawler
There is certainly some common ground here and I guess that's why I like them both. Both pickups are smooth, both have plenty mids, both are warm and organic and both are thick sounding. In some respects they are certainly related, it's just that the Holydiver is the younger and more raunchy brother. It's also important to point out where they differ because they certainly do. Where the Holydiver can be described as 'thick', the Crawler is 'fat' and on top of the warm, organic nature that is common to both, the Crawler is very rich and sweet in its tone. The Holydiver has mids pretty much across the board while the Crawler is more focused on the low mids, which gives it the darker and fatter nature that seems to be one of its defining features. While I could describe the Holydiver as 'tight', it's not a word I would use to describe the Crawler but that's not to say it tends to be mushy because it certainly doesn't, it's just that the word 'articulate' seems more appropriate. The Crawler also isn't an obviously 'aggressive' pickup but it does have a very distinctive 'growl' to it that can be really satisfying. When I bought the Crawler I was wanting to make my PRS move distinctly towards the tonal characteristics of a Les Paul and generally speaking I'd say it does just that. Cleans are certainly better on the Crawler and the Crawler also has another distinct characteristic that, for me at least, is very unusual. I'm not a great fan of single coils and I'm even less of a fan of humbuckers employing split coils but I really like the splits on the Crawler. There's some very useable single coil tones in there that I don't generally find on split humbuckers. I like the split tones on the Crawler better than most single coils I've tried.
Summary
What would work best for you really depends on what you're after. If your focus is raunchier Classic Rock, 80s Metal and more modern Rock/Metal styles, the Holydiver does very well indeed. If you need more versatility in your PRS I'd be tempted more with the Crawler simply because it has a much bigger operating window as it will cover everything from Blues to early 80s Metal and give you both humbucker and single coil tones in the process. I think it may struggle to go much beyond 80s Metal because it will start to get a little soft in the bass but there's a limit to what any single pickup will do. I use the Crawler mostly for our first set while in the second set it's far more Rock/Metal so I use the Holydiver almost exclusively but if I had to choose just one guitar to cover our entire set, I'd choose the Crawler. As for the neck pickups, the Emerald is my favourite so far because it offers so much but I would repeat that I don't really do tones that are particularly vintage. I like the sound of vintage but I miss the cut of more modern pickups. So far the Holydiver neck is as vintage as I've been happy with.
I hope this covers everything but if there's anything else you want clarifying, please just ask.
