to be brutally honest, i never liked EMGs. they're very easy to play in high gain settings (thanks to their massive compression) and guitar makers love them a lot because their tone is very stable and uniform, whatever guitar you put them on...
personally i hate them for the very reasons many crave for their typical EQed tone, their lack of dynamics and their unmistakable attack - fast but not really percussive, almost like an all-or-nothing noise gate approach.
i heard high praise on the X series, and was blown away buy a couple of Tosin Abasi videos, so i finally bought this 808X as a substitute for a bridge 808.
the EMG connection system is excellent. too bad it's not a standard used by every guitar and pickup manifacturer, so - as always - the swap has been truly fast and easy to perform.
tonewise, the 808X sounds sensibly better than it's standand counterpart. much more dynamic for sure, and it's particularly evident when playing cleans and solos.
on high gain rhythms it's almost as stable as a "normal" EMG, but the added dynamics give sometimes an impression of reduced gain. nothing dramatic, but it feels tamer.
sadly EMGs are still not my thing, and in the end i switched (as always) to passive pickups (hence my final rating, 3/5), but if you're somewhat less hostile than me to the whole concept of actives, well, the 808X could give you that much needed extra touch on cleans and leads. if you stick with highly distorted rhythms and are happy with 808s, 707s, 81s and so forth, just don't bother.