It sucks that HGVC owners have to call RCI and ask for extra vacations. It is like asking 20 questions blindly unless you know you are going to Vegas, Orlando or Mexico.
With II you can search for getaways online and many of them are a decent deal. I just found several 4.5 star Breckenridge properties (including Grand Peak 7, 8 and Marriott) during early ski season. Also found Hyatt Key West properties in Nov, early Dec. for about a maintenance fee. (wish I had more time off)
We don't plan to trade our Maui Vistana, but the access to the II cash getaways and ACs make it so we don't need to own more to get access to Marriotts and Hyatts - we can simply "pay our maintenance fees" as we go and avoid ownership headaches via cash getaways.
Would love it if HGVC moved from RCI to II but now that Marriott VC owns II, I surmise the odds are zero.