problem with the truvativ is that u need the Truvativ tool for it
http://tartybikes.co.uk/product.php?id=10150
making the total cost £50.
the only difference I can see between the onza and the trialtech is £4, the cups on the trialtech come with loctite on them and the name (snobs on here have decided that onza stuff is a bit shit, which just ain't true) so go for either.
The bearings in the Truvativ are not replaceable as well.
EDIT: If u want a nice shiny colour what about the neon at £45. Spec says it should be good...