I won't comment on the drop (not a fan of drops, frankly) but I will say the Megan stuff took the bounce out of a stock STi setup for a comparable price at the time. No idea on longevity or rebuildability etc. though.
if your just looking for a drop there are many more cost effective options. I have had some experiences with the megan coilovers though so I'll say something about them. I felt that their performance was in line with many of the other coilovers on the market, but the name always bothered me. I've never known megan to be quality parts like some other companies so I would be careful of them in terms of durability and rebuildability.(I know thats not a word)