Well, I own three MROP contracts, but all of mine have priority into a specific resort system; I'm less interested in the MROPs that have no booking priority. But overall, I consider it a good system.
MROP has been going through a lot of changes lately, and some owners are pretty upset about it. However, I think most of us are still getting good bookings through MROP. I'm less happy than I was with MROP, but I'm still quite happy. I just bought my 3rd MROP contract a few weeks ago, in fact. (I'm still in closing for it.)
The best MROP resorts and times are very hard to book; whether this will become easier under the new booking system remains to be seen. You should know that the most desirable red weeks for 2009 (i.e., SoCal summer) are already booked. However, there should be some good red weeks that are in less high-demand areas still available.
If you like VRI's resorts, what I'd suggest is booking a week with MROP, in as a large a unit as possible, and trading through VRI*ety. I think that should work fairly well.