Aruba week owners (and a few others, although not sure which) are in a different situation, since Aruba weeks can't be placed in the Trust, so the only ones available for point reservation are those where enrolled owners have elected points for the year, and many will opt to rent them since they rent for $$$$.
That said, the impact there, at least, hasn't been what was feared. When the DC was introduced everyone was assured Marriott would play fair, and only keep their fair share of each week and each arrival day even, proportional to the Trust or elected points ownership for the year. They don't appear to be hogging the best weeks or best arrival days, and I don't see a real difference in reservation availability. There have been complaints here and there questioning whether Marriott is doing the right thing, but the complaints about availability don't seem much different than pre-2010, at least from what I've read over the years. Admittedly, owning only in Aruba, may perspectively be a bit different, but my general take from thousands of posts is it doesn't appear t be an issue. Getting prime weeks has always been a "who can get connected faster" and not sure that's changed much over the years.