what do i gain and what do i lose by doing this mod

nothing much different
if u are a chinese typer, then u will lost the chinese language
unless u flash it with china main

camera is better
well, u can change everything when u finish flashing it
so theres nothing special

You get TrackID and Photofix, and maybe more patches (they will be ported to K800 anyway though).

phone is cid 53 so atm no patching at all