There are no Xtreme Blades for me to try from the 45cm Helis yet (as they constantly postpone the release). When I still used the original 34cm blades I used only Xtreme after a while - I tried all different kinds of blades, but as far as 34cm original size blades are concerned, I don''t think there is anything to beat Xtremes.
Just that through a lot of experimenting I found that for myself cutting the large blades from the 45cm helis to size to fit just feels better (to me! - which does not necessarily mean that somebody else will "feel" the same)
The cut down larger blades are wider, I leave them a bit longer and they have a much better sound (to my ears).
Once Xtreme finally releases their 45cm blades, I will experiment with those too (or in other words cut them according to my sample)

Here is an example in form of a picture: www.rcline.tv/photo/1719/my-preferred-blade-vsthe-stock-blade

I can only say TRY it for yourself and "feel" the difference. (The blades can be cut with good household scissors and just need to be treated a little with a file)

Regards,
Sven