I have a collection of steel HP100's and I couldn't be happier with them. Once you go steel, you never want to go back to aluminum. Steel tanks have negative bouyancy characteristics, which means you can drop a lot of weight off your belt. I leave about 7 pounds of lead behind.

The tanks are also physically smaller than AL80's.

As for fills with an HP tank, I have never had a problem getting a solid 3450 pound fill at a good dive shop. I have however, run into some short fill issues at quarry shops where they do fast hot-fills. I am usually lucky to get 2800 pounds at these places. However, that problem exists in the same shops with al80's, too. All in all, even at places like this, I get more gas in an HP100 than I would in an al80.

As for wearing out regulator parts, I don't know. It hasn't happened to me yet. But my thinking is that if you get your regulator serviced every year like you should, this is probably not an issue anyway.

The only downside to steel is the cost. Those babies are expensive. But since they will basically last forever, you have to look at them as a long term investment.

Mountain Dog