Yamamoto 45 is usually what people are referring to when 'yamamoto' is mentioned. It's not new at all actually, and was frowned on by scubadivers 30 years ago as it compresses too much at depth for their tastes. 'Neoprene' is also a brand name by the way.
Yamamoto 45 is great for freedivers because it is so soft, thereby sticking to the skin in a very close fit and keeping water out. This is enhanced by being 'open-cell' (the wrong term, but it's what we use), meaning not having a layer of nylon or other clothing material on the inside. The open rubber will stick to you like glue and keep water out if the fit is right. As a freediver, you can put up with some compression at depth, because you don't stay down for an hour at a time like a scubadiver- you return to the warm surface and the suit swells back up to it's normal size. However, it is very fragile and wears out faster- tears easily and loses its insulating/buoyancy characteristics.
Given that info, consider that a suit that does not compress (such as most scubadiving suits) might be better in that you would be even warmer at depth.....however a stiff-rubber suit is extremely difficult to to get on if it fits properly and may not be as warn due to less insulating bubbles in the material! Therefore a suit that was stiffer than Yamamoto 45 but not as stiff as a scuba suit would be optimal, yes?
A material with those qualities is available, and used by Ellios- it's Heiwa Medium rubber, and I swear by it. Tougher, less fragile, warm, custom fit and waterproof.
Either way, enjoy yourself.
