I think the non-SS models are less popular among collectors because the original RO was conceived and executed as a luxury watch made in stainless steel. It was a bold move at the time to produce such an expensive watch elevating the common metal to the level of a precious one in a true luxury mechanical watch. I think the identity of the RO is just so closely tied to it being produced in stainless steel and not in a precious metal.
That said, I also think that the two--tone models are realy attractive, even to me, and I generally dislike the combination of colored gold with while metals in watches. So, if you like that and you regret the sale of the earlier watch, why not go for it? That seems like a perfect choice for you.
Hunting a series-A RO is a complex process that involves a lot of research, due diligence and decisions on the part of the collector. In short, is a dream for a true collector and a nightmare for a non-collector who just enjoys watches. For the latter type of "collector," it seems to me to be a much better idea to go for a 15202 (even these are not easy to come by new from ADs as they are produced in very limited numbers). The "compromise" or "advantage" in this case, as you already noted, is that you get a caseback display, which is perhaps not true to the original solid caseback but which affords a view on the beautiful movement. Decisions, decisions. LOL.
If you want to get a "near vintage" model, as you said, you can hunt for a Jubilee edition. The hunt would not be fraught with as many complexities as it would be for an A, B or C-series RO, but you could end up with a watch that feels very special on the wrist. I guess I would go for either a Jubilee or a new 15202 choosing the dial color you prefer.
Who cares what collectors are collecting? The recent price paid for a an A-series RO is a unique piece of data and may not indicate accurately future prices in any case. That buyer may have seriously overpaid. But again, the information is not really relevant to someone looking for an RO to wear and enjoy, right?
As you rightly said, the horological hunt is where the fun is to be found, well at least much of the fun. I was reminded of that recently as I worked towards my latest acquisition.
Good luck,
respo