Here's a list of full-alter pros that I have in mind for now:
0OoMickeyoO0Yakumo YukariSiLviA, this guy was active before '12, he's not so active now, but he had the highest historical ranking (global #2 on Aug. 2012) among full-alter players.
doctorindarkSome mappers use full-alter as well, like
Sync,
Lan wings and
Scorpiour. I believe there's more.
Additionally, there are some guys doing full-alter tap/x, the only players/mappers using this style that I know are:
Black SheepAmamiya Yuko (Better known as
Skystar)
Peace, seems inactive now...
Alternative, seems inactive as well...
But right, single-alter players make the most majority group among all. There's no valid evidence to confirm that full-alter or anything else is inferior though.
Additionally, afaik most of these active guys can speak English nice and fluent (Mickey not confirmed), so you can catch them in game and ask for some advise or tips.