Hi ShookieJones!:wave: My family and I are in the same boat for our next trip...should we or should we not hit up both parties? Right now, I'm leaning toward "not."
On our most recent trip (end of Oct., beginning of Nov. 2011), we attended MNSSHP on Nov. 1st, and didn't experience a huge, shut-down-the-park, sold-out crowds (although I heard nightmarish reports from people who went on Oct. 30th & 31st). Since it was the last party, we hit the mother load of candy: 10 lbs.

! We got to MK at 5 p.m., which allowed us enough time for a quick-bite to eat and explore the party guide. My DD's got to meet more characters at this party than ever before...and met all (that they liked), in under an hour!
*Funny side note: our departure day was Nov. 2nd; while we were waiting for ME at the CT, we heard Christmas music. WDW went from "Boo To You" to Goofy singing Christmas Carols in a matter of
hours!
My last MVMCP was Dec. 2008, and my family really enjoyed the atmosphere. However, I don't think it will have the same feel in the beginning of November, because not all of the decor will be out.
As for crowds that time of year, it will be very tolerable-to-moderate-to-heavy (specifically on the weekends at EP due to the F&W Festival). In fact, we steer clear of EP on the weekends, and find that F&W is tolerable mid-week. Also, schools in NJ get out for a week in the beginning of November, which has been noted on Touring Plans "Crowd Levels." Comparing the levels to May is about the same (except the weekends at EP).
Who knows...we might change our minds (if budget allows) and hit up both parties, because how often does that happen? I can't imagine the first couple of MVMCP's will be that crowded.
Happy planning!:sohappy: