II actually see the opposite -- 60k RIV vs 100k GFV -- Where RIV has been on sale for 3 years and GFV new sales just launched recently. To me, that's RIV holding up pretty darn well. I would have expected a much bigger gap.
In April, it was GFV 178k and RIV 93k.
So, in April: RIV sales were only 52% of GFV sales. In May, RIV sales were 60% of GFV sales: In other words, as you move past the initial surge of new buyers, the gap is closing.
Also in May -- GFV sales dropped 44%.... RIV sales dropped only 36%
Regardless of any re-sale restrictions, GFV is going to be selling better than RIV right now. As long as the pricing is close, the flagship monorail resort is of course going to be more sought after than a skyliner resort. (Yes, there are lots of people who would prefer the skyliner location but honestly, the majority still prefer the monorail location). And GFV just came on sale, RIV has been on sale for 3 years.
Considering these factors, RIV sales being 40% less than GFV sales isn't really surprising at all.
The best comparison -- the last time 2 WDW resorts had overlapping sales -- around July 2019. RIV was about a couple months into sales, CCV was still offering incentives: RIV was 108,675 vs 52,837 for CCV -- so CCV was 48% of RIV sales.
The newest resort always sells the most -- The question is, how well do the other resorts hold up.