>>469039I would recommend teaching in kit similar to what your shop rents. You want to be in identical kit as the students, although you may want to show them the setup on the last pool dive and maybe try it out.
Twinset : Apeks TEK3
Singles : Apeks XTX100
Singles, pool : Aqualung Conshelf XIV
Vintage : DA Aquamaster doublehose
>>469040Economics.
Helium is expensive. $200-$300 in helium for an open circuit deep dive turns in to $10 in helium for a closed circuit deep dive.
The payoff for rebreathers is if you do a lot of deco diving or diving past 90 ft consistently.