Hi Ron,
yes, the lungs are seperate compartments. But you have to check if it's not to heave with lead. Hopefully I can make a trydive with the ray in two weeks. If I remember correctly my wife needs about 10kg of lead with the Ray in SCR mode.
Maybe there will be some answers about the lead.
http://www.rebreatherworld.com/semi-...y-weights.html
Have you ask Holger (TR300) about the weight of the TR300sc? It should also be very light.
Or maybe this one:
Stingray CCR
Cheers!
Christian