cheers andy! should be fun...
trance generally has to have 'something' to it to make exciting i think. TBH i haven't heard a lot of sean tyas, but i have liked it, i'm not bagging the guy... i appreciate his production values etc, it's a nice sound. i just think you have to be wary, as someone said above, to produce too many similar sounding remixes etc at around the same time, otherwise your sound will stagnate, and people won't want to hear it any more...
re: armin etc, communication is a bit of an exception because that was his breakthrough track... from then onwards all of his remixes and originals have had that same feel- the 'rising star' type sound. i think the trick with armin, though, is that his sound is neutral enough to be able to get away with only changing it subtly to make things sound fairly different...
ferry corsten has done well to have 2 distinctly different styles, i think... system f/gouryella VS flashover sound...
i don't think tyas has shown either of ^the above^ yet.
gc.