None of it is difficult, it's just different and you need to understand it. For example, there is no purge button so you have to clear the hoses in one of several different ways. More than I want to describe here but you must learn how. Diver position has a lot to do with how the reg performs, which is something you need to learn to use to your advantage. The best way to learn is to mentor with someone who dives DH regs but learning all you can about them from reading, experimenting in a pool and asking questions on line is also very helpful. I would suggest that anyone interested in DH regs, be they vintage or the AK come to the Vintage Double Hose forum. New DH divers are always welcome and there are lots of active DH divers there who are happy to help. SB is a great forum for all things scuba but VDH is a lot more specialized. DH diving is a bit different but I find the rewards well worth it. I find them more comfortable, fish are less scared by them, they are quieter, bubbles do not get in the frame of video or photos and the cool factor, a lot of divers are curious about them.
For anyone interested in DH diving, this is a good deal for a great reg.
For anyone interested in DH diving, this is a good deal for a great reg.