Since starting my slow journey back to the present age of scuba 2024 and what I have learned , do not go beyond your limits of your phyical and mental abilities. Rebreathers are probably out of the question for me unless there is a big pot of gold and jeweles to be found . I was offered rebreathers back 30 years ago but had a problem that my monoamine oxidase A was out of wack . There was this cigar smoking air controller diver from Florida that offered me to be his buddy except dead divers were a trait of his and so I respectively declined . So where does all of this goes , Get the training and only with a clear goal , being tactical and advance with a purpose to be achieved . Be safe and have fun. Rumdumb