I could be wrong as in my AEG I have zero air seal problems with the W-Hold, but the FPS drop (to my knowledge and experience) comes from the larger mound of the W-Hold, causing more friction on the BB. I've never had any performance issues with them regarding air seal and when I turn hop all the way off my FPS goes right up to what it should be at around 395+/-2FPS.
Maybe I'm lucky?
I know I get the same results with my GBBRs using the PDI, and same thing when I use the Reaps A+ rubber. When I engage hop to the right setting I get around a 12FPS drop with both rubber types. Doesn't affect range or accuracy in any negative fashion, only dat +.