We own HGVC and non-HGVC TS's and I always figured HGVC were more costly.
In a conversation I went through and looked at the cost per point (including MF's) for each of our properties using RCI as the common exchange rate between them all. What I found was that while HGVC was a bit more expensive, its only by a little. Effectively costs of staying at the HGVC's and non HGVC's were on par with each other.
The HGVC system however is very, very flexible. The company is a class act and the properties all shine no matter which one we've stayed at. We've used our non-HGVC's to exchange in to other non-HGVC's and I can say while some were nice, many more are good to average.
One of my three sons is getting married New Years Eve and we've already been told they'd like to take us up on our offer to give them use of our HGVC timeshare to go to Hawaii. I expect as time marches on the TS's will be increasingly popular with them as they learn how nice it can be for comparatively little $$, particularly using ours.
I'm glad I have both in & out of HGVC, but the HGVC's are really the nicest of our collection.