I spent three days on Catalina playing with the Piranha, and if I had the purchase price burning a hole in my pocket, I'd already own one.
The scooter is ridiculously simple to put together. No latches! Pressure holds the battery module in place, although there is a safety strap you install. The primary purpose of the safety strap is to make the perfect handle on the scooter nose.
The thing is TINY and deliciously light. For somebody short, like me, the Sierra always presented a challenge -- I had to hike my arm up to keep the nose out of the sand, if I held the shroud. The Piranha has this nice strap, and you snuggle your hand under it and stand up and presto! Scooter is off the ground and easily carried. I don't think it weighs any more than an Al40 deco bottle rigged up. I can carry it into the water without worrying about my balance.
It goes like a bat out of you-know-where. The Piranha I had, in first gear, was outrunning a Sierra with a similar sized and equipped diver in 3rd. And it is agile as a good backfield runner. I did my first truly successful barrel roll (you know, where you don't pull out of it screaming and trying not to run the scooter into the sand) with the Piranha. I did loops and snap rolls and spun myself silly. It's so short, you can aim it anywhere.
Downsides? Two, only, that I can think of. One is that the one I was using was NOISY. I mean, you have to put up with scooter whir with any scooter, but this thing sounded like a Vitamax mixer on high. Dive X-tras tells me this prototype didn't have the gearing the sale models will have, so they will be quieter. I'd put up with the noise for the light weight and the maneuverability and the burn time. The second downside is the price. For what a Piranha costs, you could take a GUE open water class AND buy all your gear, or spend a week on just about the fanciest liveaboard ever.
In case it isn't clear -- I loved this device. I loved the simplicity, and the lightness, and the handle, and the speed, and the fact that you can do a whole day of diving with it without swapping out batteries. If I could trade my Sierra straight across, it would already be done.
