Agree with the Capt.
I have the XTX100 (a few, actually) and love them. I started out moving them back and forth between yoke and DIN single tanks with and without the yoke adapter but eventually went with one of each because the adapter moved the first stage too close to the back of my head. Once I started playing around with doubles I went with two DIN first stages, plus a yoke first stage for single tanks and travel. You can move hoses around and even convert back and forth between DIN and yoke connectors, but I decided it was simpler to have a set of travel regs and a set for doubles. Call me lazy...
There isn't much difference in second stages between the 200, 100, and 50. There is also the 40 which is similar except that it isn't adjustable. They all come with both the wide and narrow exhaust tees; I use wide for the primary and narrow for the bungeed backup.
The first stage of the 40 and 50 is the
DST which has the the LP ports on a rotating turret. I had a TX50 with a DST but found the turret would let the hoses rotate at exactly the wrong moment, usually gearing up. I was happy to be rid of it. Maybe I'll change my mind later if I need stages or a deco bottle, but that's not an issue for me right now.
The first stage on the 100 is the
FST, it has a very low profile on a single tank with the diaphragm down, and great hose routing. Its also great for doubles with the diaphragms turned in. My favorite, I'd buy these again.
The first stage on the 200 is the
FSR, in addition to the chrome also has good hose routing for singles with the diaphragm up, but isn't as low profile as the 100. It has a removable valve seat that the FST doesn't have.
There is another good first stage, the
DS4. If you google "DS4 hose routing" you'll see some people don't care for doubles routing with certain tanks and manifolds. But the price is definitely right. I've seen more of these than any of the other Apeks first stages combined.
In spite of how much I like my XTX100s, IMO the Status models are scuba gimmickry at its worst. For less than $25 you can buy an
intermediate pressure gauge to connect to your inflator hose that will give you more useful information that the Status LEDs ever will. IF you check around you may find the Status models will sometimes go cheaper than the non-Status models because nobody buys them.
As far as where to get them, they show up used occasionally here and on TDS. LP sells them only as a set with one second stage and one (yoke) first stage, and the DIN conversion will cost you an extra Grant. Aqualung seems to have a new policy with the Apeks stuff; they don't want to sell you just an extra second stage (vs. and octo) or just an extra first stage. FWIW, DI sells sets and components.
If you get the older ATX models, be aware that most of them come with first stages that had that one goofy 1/2" LP port that you'll either need to plug, get a converter for, or buy hoses that have one connector with a non-standard sized fitting. The DS4 never had the 1/2" LP port, so that's not something to worry about. In fact, you could probably save quite a bit of money getting something like ATX50 second stages with a DS4 first from someplace like DI.
Best of luck.