I think it's almost a no-brainer for you with the amount of time you ski in Summit County. You can always downgrade to the Colorado pass with 10 days at Vail / BC next season buying on-line saving about $ 150 if you won't need unlimited days at Vail and Beaver Creek.
Not living in Colorado I still got an Epic Pass 2 years ago. Skied 18 CO days. Skipped Colorado last year (SLC gathering yea!)
This year I planned to ski CO a lot but I found the price of the Epic Pass was up a lot. No problem when I found they'd let me downgrade online to a Colorado Pass
even though I skipped a year. Works here.
Since I renewed in April they're allowing me unlimited Vail & BC days in April 2011 ! Perfect for the gathering.