Tbone has provided a really good summary of Apeks regs - 1st and 2nd stages - in Post 8. I will add a couple of comments based on my own experience with Apeks, and some admitted personal preferences.
- 1x Apeks XTX200 second stage (my primary) - also open to the XTX50 but was thinking the dual porting might be nice for future SM or tec options down the road in a few years
- 3x Apeks XTX50 second stage (My GF's primary and her octo, plus my octo)
I see no point in buying a XTX200 2nd stage. The difference between that and the XTX50 is cosmetic. I would go with 4 XTX50s. I have 20s, 40s, 50s, 100s, and 200s. For my money the 50s work well for everything I do, recreational and technical. Having said that, an argument could even be made for the XTX40, which is identical in performance to the 50, but does not offer a User Adjustable Breathing knob. While I have UAB on almost all of my second stages, and personally prefer having it, I seldom use the adjustment to be honest. And, others on SB have made the same comment. Yes, I suggest the 50 across the board for you and your girlfriend. But, if you get a deal on a 40, think about it.
Can't seem to find a bundle that has the DST. And then I see they also have an Apeks 5 port adapter kit...
It seems odd that you can't find a reg set with an XTX50 2nd stage and a DST first stage. That is actually the 'preferred' Apeks packaging (even noted on their website:
XTX50 Regulator). There isn't anything wrong with a DS4 / XTX50 pairing, I am just surprised that you are having difficulty finding a DST / XTX50 boxed set. For years I have dove some swivel / turret first stages, including the Zeagle 50D (the Zeagle equivalent of the Apeks DST). They work fine. I don't see any conspicuous advantage of a swivel / turret for single cylinder, backmount diving, but there is nothing wrong with them, either. I don't see any substantive advantage to adding the 5th port, either. I have a DST with a 5th port, and one without, and hose routing with either is easy for single cylinder bacvkmount. One caveat in your case: you do mention the possibility of expanded diving in the future, and a DST, and a 5th port, might serve you particularly well in the future if that turns out to be the case.
Finally, I'd want to snag a DIN to Yoke adaptor.
You can 'snag' an inexpensive one on eBay - there really isn't any need to pay a full, new price. And, there isn't any difference of note across adapter brands. I have Zeagles, Dive Rites, and Apeks adapters, and dislike all with equal enthusiasm, for single cylinder backmount diving. They are a pain in the neck, or more specifically, in the back of the head. I dive DIN cylinders at home, and am forced to accomodate yokes when traveling to the Caribbean. But, instead of using an adapter, I simply convert my DIN DST or 50D to yoke (takes about 30 seconds) by swapping out the DIN bolt for a yoke bolt, and adding the A clamp. That may be beyiond where you are right at the moment, but it is something to think about in the future.
- 2x full sets of hoses (mine + my GF's) - I want MINE to be GUE/DIR compliant. I think she'll likely stick to standard PADI but she might be open to swapping to the DIR philosophy here
I am not sure I would give full credit to PADI specifically (or any other agency) for a 'standard' hose routing
), although I know what you mean - 40" alternate second stage hose, shorter (usually 36") primary second stage hose, etc. But, I would encourage you, to encourage her, to adopt a better approach right out of the gate with new regs, i.e. a shorter hose on the alternate second stage, with that stage positioned right below the chin on a bungee necklace, and a longer primary hose suitable for donation in an OOA situation. For that matter, that longer primary hose doesn't have to be a 7' primary, or even a 5' primary - you can configure a much better approach with 'standard' hose lengths. Simply use the 36" hose - formerly the primary - as the alternate second stage hose, and use the longer (40") hose as the primary. Those are not ideal lengths but still better than a 'standard' configuration. But, since you are looking at buying new hoses for new regs, why waste money with 'standard' lengths. There is a definite (and I think, inexorable) movement toward a 'primary donate' regulator configuration in recreational diving and you should configure you regulators in a manner to facilitate that approach. Whether you call it 'GUE/DIR compliant', or something else, the configuration remains the same. Even PADI is showing signs of moving in that direction
)) - the changes in the PADI OW program implemented several years ago emphasize 'active donation' of the alternate second stage, rather than simply passively allowing a stressed OOA diver to search for it in the (Bermuda) triangle.
I appears that you are looking at DRIS as a possible vendor. I agree with tbone - call them up and discuss what YOU want, and ask them for an 'all in' price. Don't simply look for, or accept, the bundling approaches you see online. A competent Apeks dealer can get / create the configuration YOU want, rather than just sell what they have.