I have a turbo mounted Banks and I am pretty happy with it.
I also have a Banks Brake. I believe it is the best flowing turbo mounted brake available. Still, it limits one to just a few turbo choices. With a DZ 14 Mach 3. 8's & my APB turned all the way up, I've never been able to reach 1300* egt. Then I don't tow more that 10K lb & that's horses which I baby. No racing the PowerJokes with my horses in tow.
As for the performance of the Banks Break; it has a lot of stopping power. Sure it turns off at 15 mph but I don't see that as a problem. Sometimes I wish it turned on at 25 instead of 30 but I can live with that.