Steel or aluminum? High pressure or low? Our op in Cozumel uses steel, high pressure 120's, (15l) and the only difference I notice is on the boat. They are large. Once you are in the water, I don't notice the difference and they remain negative throughout the dive. Some smaller people notice they try to roll them, but moving trim weights to pockets usually cures that. My wife is 5'4" and dives one with no issues.
Depending on your personal air consumption and depth, insanely long dive times are possible compared to standard 80's. We love them and have had 90 minute dives. If the dive op requires everyone to surface as a group, the limiting factor will be the diver that uses their air the fastest so the larger tank my not matter if you don't need it. Our op will have the DM sHare their air if someone hits 1000 psi long before the rest and will sometimes bring a pony for serious air hogs.
Best thing to do is try one.
Good luck, safe travels,
Jay
