Personally, think it's got tons of power for it's size-I must say it's moves me along very fast when I'm snorkeling-not as much with tanks but still does the job fine. I'm usually hunting or scoping out areas anyway and rarely even use it on 3rd speed.
You should really try one-I bet you'd be surprised. It only weighs 10 pounds-has tiny footprint-amazes me ever time I use it. And beyond simple-pretty unheard of in the scuba industry.
For example, I tossed one in my carry on-flew down to Fla., rented a few tanks and hit the 2nd and 3rd reef at Lauderdale By the Sea. Had a total blast-tank of air lasted forever-and didn't even feel the current. Also, the Blade makes a terrific platform for a camera for pov shots on the fly. I mounted a Panasonic DMC TS2 on mine and got some cool footage. That's the BladeFish in a nutshell.
There are lots of good DPVs on the market(I have most of them in my garage) and the BladeFish 5000 fits into the pack as the compact, simple, dependable and fun choice.