We've done tihs the last few cruises we've been on and found making the reservation effortless (to be clear, we usually do something like paying for our kids with points and us with cash).
The difficulty, though, comes if you want to CHANGE the reservation. We tried to upgrade to concierge and
DCL wouldn't talk to us directly. We had to call DVC, who called DCL, and so on. Game of telephone that's not needed since it's one company.
All in all we think the points are relatively good value and we've always found availability.
Good luck!