Rebreathers are great for extended range in either depth or bottom time. I'm not a
deep tec diver yet have found them to be very enjoyable.
for example:
I like diving Day Island wall, a favored local dive site in Tacoma WA with a max depth around 130 FSW. It requires a hefty swin, easiest under water but hard on air consumption. It often requires dealing with anywhere from mild to extreme current, also hard on air consumption. On OC it was an hour dive at best, with only a short time in the deeper realm where all the octos and wolf eels are.
On a rebreather and a favorable tidal exchange, I have been able to do a two hour dive on it and only used up about 2/3 of my gas capacity and only racked up 5 minutes of deco (which was totally gone long before the stop). Swimming out to the wall was no problem, I didn't really need to worry about how much gas I had. I saw many times more of the usual critters since I could go at a steady and slow pace and did not sound like a train going through everyone's back yard. I got to stay down deeper, much longer due to the decompression benefits. I spent most of the dive between 130 and 70 FSW...for a two hour dive on OC at that depth you'd be into multiple mixes and multiple stops to pull that off.
For me Nitrox was the gateway gas on the way to rebreather diving, where you don't have to calculate the MOD before the dive, you have lots of options.
The other thing I've noticed is that I do not get so fatigued from diving, my muscles don't ache so much. It's probably because my core temperature stays warmer and because I don't take on so much nitrogen, and the little that I do I off gas mostly before even getting to the surface as my o2 fraction gets richer and richer as I near the surface. by the time i'm at 15 ft i'm near 80% o2 in the mix.
it's time consuming, cost quite a bit to get into but for those who just can't get enough from OC, it's well worth it!
