Still can't figure out if good deal or not. 20k pts = $560.
Take a Cat 2 Hotel. A 5 night stay would prob be about that so you are getting about equal value. Looking at higher hotel, it's also about same value for pts to $...(Cat 6 W Union Sq, I see it about $400-500 so again breaking even)
With Marriott the 50k pts for $600 you buy can get you a $1000-1200/night hotel at times (and has). And for lower awards you also come out ahead. So there's a clear advantage.