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I do not think the OP is talking about vintage diving It is not a problem with BP/W
Actually for some types of diving where your exposure suit is buoyant and steel tanks they weight pretty much the same as the single tank setup and a pony bottle
Unless you want doubles to spend a lot of time shallow in warm water, cylinders are just the beginning. A lot changes when switching to doubles results in deeper and longer. For example; training in decompression and gas mixtures, dry suits, more $ophisticated computers, additional regulators, a different BC and back pack, stage bottles, extra sets of doubles, and maybe giving up shore diving because all this gear is pretty heavy. A $600 set of doubles can turn into $5000+ pretty fast.
I am not trying to discourage you, but you need to consider the big picture. I would probably go with doubles because I like wrecks, but that money can also buy tropical dive vacations or a small boat all of which are holes in the water to pour money in.
I am just interested in learning the right way and making sure I dont miss anything in the process.
Only until you have exhausted shallower dives in your area would I personally gravitate to doubles. They basically only exist to dive deeper which you should not be doing now anyway. They are far less streamline than single rigs, etc., etc.
I would progress by taking fundies in a single rig this year then next summer work on doubles tech pass. Just my 2 psi worth..
+1
...I see so many people who dive doubles because of the image, not because they need the gas. The divers who do this have all kinds of justifications, too, that ring hollow when you really dig at them. <shrugs> You might consider this part of your first real technical training: a realistic assessment of your equipment needs.