I'm in Cozumel, typing on my tablet, so I'm going to try to be brief.
The Hydros is super comfortable. It's more stable than a bp/w (because it doesn't shift around at all). It's a little more convenient, because of no crotch strap (and no need for one). The bungee setup keeps the (overly large) wing reasonably streamlined. It dries extremely quickly. It is much easier to throw on and fit it to your body in seconds. It's not floaty at all. It may even be slightly negative.
All that said, I didn't bring it with me here to Cozumel. I brought my Freedom Contour plate and wing. The Freedom plate is almost as stable as the Hydros, equally comfortable, and I couldn't resist being the third diver on the boat using a Freedom plate.
