I bought SSR about 5 years ago and there has roughly been a $20 price drop since then. I will be curious to see what the next 6 months hold.
I think it depends somewhat on what comparison you are using. I bought SSR six years ago at $83. Looking at the ROFR thread, it looks like SSR is generally selling around $60, which would be $23 less than what I paid.
However, there have been numerous ROFR clearances below $60 including several at $50 and one at $48. The most recent one at $50 was a 200-point contract, fully loaded.
So I'd say there has been a significant erosion in SSR prices over the last six years. I didn't check prices, but I really think there has been even more at AKV since sales opened there. And, as Ryansdad0727 noted, a LOT of the drop has been in the last year or two.
As far as any effect from the change in perks, I think it's too early to tell.
I don't expect the prices to crash, but I think they are going to steadily decline -- not because of the perks change, but because Disney is not ROFRing much, and the economy stinks. Those two factors are what will drive
DVC resale prices, IMHO.