why does that call for DIN? I know that it is preffered among the tech community for allowing higher pressures, but what exactly is the difference when ice diving?
The specific technical reasons have been addressed, but a number of people prefer to go DIN just because they are a bit more secure. I know, that sounds almost condescending, and that is not the intent. My first reg as a newbie diver was DIN, virtually all my regs (except for a used pool reg and a used reg I put on my drysuit inflator bottle) now are DIN, and I just feel they are a bit more secure in any environment. In reality, though either DIN or yoke will work well, and if you have convertible valves, you will have the option, even to mix first stages (one DIN, one yoke).
So are doubles DIN? Would I be fine mounting two yoke first stages on a set of AL80 doubles
We had a tech student complete the PADI Tech Deep course last year, diving double AL80s, with yoke regs - because that is what he had. Worked fine.
Not a bad price for a new set, except the shipping would be a bit of a bear. One of my favorite sets of BM doubles for freshwater, drysuit diving is an older set of AL80s. Not too heavy, great trim, enough gas for long, fun NDL dives, etc. I also use them for coastal wetsuit recreational diving.
Sidemount would be getting techy, and this is why for me simply doubles seems logical, especially considering I would like to get into ice diving.
I think a reasonable case could be made that SM doubles are actually less 'techy' than BM doubles. But, that would take the thread off in a different direction. Instead, I would encourage you to not totally discount SM as too much of a tech option.
TS&M:
Executive summary: Go with DIN, either 200 or 300 bar will do, aluminum 80s are fine in fresh water, and if you are going to ice dive, get some training.
Ditto! Well said, Lynne.
Now, a bit of heresy - there is nothing wrong with thinking about doubles early on. I fully agree that a lot of valuable, enjoyable, developmental diving can (and should) be done with a single tank. (I thoroughly enjoy training / practicing in single tanks, as well as doubles.) But, for some people, part of the excitement about diving is the gear itself. When I had 25 dives, I was already thinking about where I could try out a rebreather (never did, by the way), just because the idea seemed interesting. Several, more experienced divers told me I shouldn't be thinking about that so early, and pointed out all the dangers. Now, PADI has an option for doing initial OW training in a rebreather. With any gear configuration, the critical element is to learn how to use it properly, and that does NOT mean you will be expert the first time you use it, even if you take a class. My first drysuit dive was #31, and I certainly had not mastered wetsuit buoyancy and trim by then, so much of my B & T development was done in a drysuit. My first BM doubles dive was ~#190. I set the doubles up myself, with a little LDS advice, and went off to the local quarry. These comments are not meant to suggest in any way that a cavalier attitude is appropriate when trying new / different gear configurations. Rather, 1) there is nothing wrong with dreaming, exploring, inquring, testing, early in your diving and 2) there are many ways of learning (I really applaud saxplayer's comment about mentoring) beyond formal classes. My dive buddy / fellow instructor and I are taking a younger acquaintance out for his first doubles diving this Sunday (and loaning him a set of BM double 100s and regs). In this case, we have a bit of experience diving with him, so we know his skill level. But, he is well below 100 lifetime dives, and has been thinking about doubles for some time.