I'm thinking the same about jump from T4, but by reading many posts here at the forum, it's probably just going to be just fine, even sound better.
Some small adjustments in settings and soundchanges have to be done to fit personal taste, but I think Genos will adapt older stuff in a good way.
Myself I will try out Genos without any changes at first to see whats in it to use "as is", and then try update what I have to come close to my liking.
As far as I have heard by now, the Revo drums alone do a great upgrade.