Ron Brandt:Actually,I put my students in them for all reasions you mentioned but.... steel 72's.
I am also thinking the poster is refering to steel 104's or up to 121's used for cave....you will not need a weightbelt with a typicle 3mm wetsuit and actually may not result in a balanced rig or be able to swim to the surface should your bcd fail (IE no ditchable weight).
Aldora and Liquid Blue use HP 100s and 120s. They are also careful not to let the diver overweight themselves. I had a leak at the pull dump elbow in the 100 and had no problem keep myself off the bottom at the beginning of the dive while my buddy fixed it underwater.