I'm currently on Adrynalyne's 6.5 4.01 ROM. I was using his 6.1's. I haven't found any problems nor real differences in performance or stability between the two. The important thing was to get off of the stock ROM.

I wanted to try the Titanium interface in 6.5 but frankly have been so happy with the way I have SPB Mobile Shell set up that I have yet to see any advantage to Titanium although I admit to not spending much time trying to customize it yet.