I think Aspen and PC get about the same amount of snow. I don't think it is a "bad" idea. There should be plenty of terrain open at PC and if snow is lean, you can always make sure you rent a car(cheap in SLC) and you can eaily drive to Little Cottonwood where you are pretty much guaranteed skiable snow. Naturally, Christmas isn't the best time to go because it is a holiday, but then, that is why you are going, because it is Christmas, so ignore the negatives and enjoy your trip.
I've been there the last few years between the day after Xmas and a couple of days after New years. I generally ski a number of areas including PC areas, but it's really not that bad in terms of crowds. snow generally okay to great. always gotten snow sometime during trip so far.
To avoid crowds, and if you are dedicated to the PC resorts, hit up the canyons. If there is the dreaded line at the Flight of the Canyons gondola, take the 1 minute hike up to the Golden eagle lift. If you have a car, and don't mind a drive, Powder Mountain is never crowded, no matter which holiday or day of the week it is. On their busiest days of the year, you might have 6 people in front of you in lift lines. You might have to wait a chair or two.
Aspen Mountain doesn't have many lines. Highlands almost never. Snowmass is the most popular and used to have some coming out of the village in the am. But they put in a gondi and a HS six pack and they pretty much fixed that.
I haven't been to PC at Christmas, but I would be willing to bet it has bigger lines. DV has a rep for no lines. But at the end of the day as they close the upper lifts, everyone gets funneled down to the Crown Point lift you have to take to get back and I've been stuck in a huge one there?
I have skied Deer Valley many times during xmas.... Matter of fact, I ski somewhere every Xmas with the family and there will always be lines... Not much you can do about it....
My suggestion .... Ski early/ first chair,,, (all the holiday people are sleeping till 10am),,,, then eat lunch from 10am to 11am when the crowds start,,, get back out and ski while everyone is eating lunch from 11:30 to 1pm ,,, then relax from 1pm-2pm have a beer,, finally ski till last chair..... That always works for me.....