The down side is less miles per tank. On average, I get 12-15 miles less now' except when I am all highway. Then it is about the same. City commutes must have too many WOT moments on Brahma.
The Decel popping I had after the Triumph TORS tune has gone away and I can feel more get-up-and-go. I have not put it on a dyno ever, but the seat of my pants tells me it is improved.