It's the same deal.The 300 dollar pass for ten days is good at Vail and Beaver Creek, as well as the Summit County areas of Breckenridge, and Keystone. The big difference would be the crowd situation at the Summit County areas on Fri., Sat., Sun., and Mon. , and the added convenience of additional areas in the Roaring Fork Valley where Glenwoood Springs is located. The skiing at Vail/Beaver Creek is a notch above Breckenridge and Keystone, and you could still wander across Vail Pass mid week for a day or two of skiing at Copper, Breck, or Keystone.
That said: There isn't anything else in Colorado that compares to the terrain, versatility, infrastucture, and convenience of skiing the Aspen group for the day. If you are doing it on a budget, you can easily ski multitple mountains in the same day for the price of one lift ticket. The terrain at the areas previously mentioned just won't stack up to what is available, and it shouldn't be missed by anyone who wants a serious sampling of Colorado skiing. If budget conscious decisions are part of the mix, it should be noted that Sunlight offers very reasonably priced midweek skiing similar to Ski Cooper, but with terrain that is a couple of notches up from the 'family picnic' attitude of Cooper.
For a month or more of skiing in Colorado, I just find it hard to see how Summit County is the best choice. It has been my experience that after sampling the rest of Colorado, Summit seems a little confining after just a handful of days. Good Luck on your planning!