If the Evo 4 is as torquey as the 3, it is plenty powerful on the top end as well.
I have the RB T10 and when I had it running it was ballistic as well - Novarossi style
I have heard that the issues Picco had earlier, like blowing rods (evo 3), they had sorted all those problems out and its all good now.
I guess it comes down to parts quality, and Novarossi definitely have that hands down.

If you dont know why, its because RB have their engines made in the same place as Novarossi, thats why RB plugs are almost identical in shape to Nova plugs and the carb rubber boot has the Novarossi logo on it. Unless they have now got a different factory where their engines are made, then... yeah, you get the picture?