I always liked that they will (or at least would) essentially build whatever the hell you wanted no matter how crazy it was
Judging from the stuff I've seen on the internet the quality of them is inconsistent.
I do have a friend who ordered a custom fretless semi-hollow Skatecaster-esque...
I purposely opted for a Floyd Rose Special when I built my Warmoth because it was the only floyd I could find at the time in satin chrome.
Mine has been fine; definitely a step up from most of the no name licensed trash from the 90's in my opinion.
Just be more careful with the lock and saddle...
Closest I've came to testing this was with my buddy's old Epiphone SG - we removed the stock covers from the pickups and they 100% sounded brighter and more aggressive afterwards. It was a clear difference.