I saw your concerns under the "500 Kingdoms" thread. I have never traded into RCI, but I think that's sort of besides the point. Here is what I would suggest:
1) The "500 Kingdoms" thread is a specific reference to a new
DVC marketing campaign. The criticism that you should take from that thread is that RCI is an option, or a perk. To make it a selling point is, frankly, a bit misleading. While trading into RCI is allowed and viable, it's not so easy as to suggest that you can pick up the phone and be whisked away to "500 Kingdoms".
2) Trading into RCI (I have read countless threads on this) take a lot of planning, and flexibility. Can it be done? Of course. Is it easy? Not really.
3) The RCI selection consists of approx 10% of the RCI resorts. From what I have read, it's not the 10% at the top. There are some real hit-and-miss stories around these threads.
4) If you bought into DVC "in part because of the ability to use it to travel to non-Disney properties", I would suggest you reconsider your purchase. That is, of course, unless you mean every once in awhile. But if you are hoping to make a sporadic Disney trip in between 2-3 RCI exchanges, I would not say it's impossible; I would say it's impractical, and not a good bang for your buck.
5) The RCI exchange, like everything else, is a "perk" and perks can go at any time. I'm not suggesting it will go away, but you have to buy DVC with the implicit understanding that you are buying access to one Disney resort.
You will find RCI success stories. You will find stories of frustration. I would look past people individual successes/failures, and focus on the big picture: Why are you buying DVC? If the #1 reason is not to vacation on Disney property, then you might be making an imprudent decision. Conversely, if you want to travel mostly to Disney and simply are hoping to have the flexibility to trade out once in awhile? Then stick with it.
I think the DVC salesman exemplified the nature of the "500 Kingdoms" thread. They are selling people on the notion that Disney is just a footnote in the list of options that DVC provides. While technically this is correct, it's misleading.
One thing to consider. A lot of people find tremendous success renting out their points, and renting is very easy. Let's say you have 200 points; you can rent them very quickly for $10-$12 per point. You can then take that $2000-$2400 and get yourself into many resorts with a cash reservation far more easily than via RCI exchange. We have family friends who recently rented out their 500 DVC points for $5500 and use the proceeds to pay for 3 last minute cabins for 6 people on a Royal Carribean cruise.
I hope I'm getting my point across, sorry for all the rambling. In short, I'd say that you should buy DVC firstly as a mechanism to stay on Disney property. There is flexibility to the membership, you can trade out, you can rent points and apply the cash towards other vacations. I just wouldn't buy DVC if trading out or renting was my primary intention, but instead is just a once-in-awhile option.