@Protondecay123 Reading your chart, would the LP108 (top row) also be mostly negative following thirds? 8 lbs from empty to full, so using 2/3 of your gas would mean you end the dive with each tank a third of a pound buoyant. Usually not happening if you've got flow pushing you on the return trip. Considering that those tanks are going to be overfilled, the buoyancy when filled will be higher by a pound or two (lets say filling to 4/3 service pressure (3520psi), so 8lbs*4/3 = 10 2/3, so the filled buoyancy would be around 7.6 lbs negative, etc). I guess in conclusion, it seems to me that the buoyancy characteristics between a HP and LP tank aren't too significant when cave diving.
Buoyancy aside, what other reason would I want high pressure tanks for? Many places outside of Florida are barely capable/willing to fill HPs past service pressure, right?
Correct me if I'm wrong on the weight calculations above, I know some more advanced stuff comes into play with gas types and pressures and stuff. Also, if it wasn't inferred already, I'm gonna be cave diving with whatever I get.