I would agree that most of the time you get to keep the points, but it is not guaranteed. I have done two shops where I did not get to keep the points - both were Hyatt brands actually - but I have also done Hyatt's and not had them taken, so that is not consistent either. It probably is more about who handles the reversal and how they handle it, as Steve suggested.
In general, I would say you can probably assume you will get to keep them; however, there is a always a possibility that you won't - and in that case there is nothing you can do about it.