Not many MCC's offered in comparison to Stack's...but again, high grades won the bids whereas low grades or omp were passed on. For example, a 1992 proof set with 2 67's, 2 68's and 1 69 did not get an opening bid at $9500.
Also, the 1988 Hong Kong gold medal hammer price in PF69UC was $6,000 plus a buyer's premium...I believe one is being offered on the forum for $11,500!!! However a 1995 gold panda proof sold for $16k in PF68UC, plus premium...This is higher than the $15K from Stack's for a 69 vs. a 1995 gold unicorn PF69UC sold for $7K plus BP (this is alot less than Nick's asking price of $20K)
Again, high fliers are coming back to earth... Also, it is possible that with all the auctions over the past 2 years, many many coins that were never seen have come to market. This would diminish their rarity factor as what once was seen as never available is freely available several times per year. The good news with softer prices is that maybe the auction houses may slow down their offerings which will severely limit supply in the future.
Hang on to your high grade MCC's, I see a trend coming.