The problem with planning around black out dates is that the Deluxe AP only has holidays and Saturdays blacked out, so that may not work as well.
The Deluxe AP also blocks out after Christmas through Saturday, January 2nd, and around July 4th, as well as the Sundays before what appears to be Memorial Day and Labor Day, and Valentine's Day weekend. It is valid on Saturdays in October and a few other months, though.
You never know what crowds will do, especially with Disney giving out admission so cheap to locals--3 days for $99 is probably drawing a lot of people who aren't the type who would want an annual pass, and those don't block out on any Saturdays, just July 4th. And most of the non-blocked dates before Christmas, school is still in session, while the dates after Christmas, school is not going for most students, so the tourists visiting after Christmas may make the crowds much larger--that's certainly what has happened traditionally.
But yes, even though it's all guessing, I would take all blockout dates into account (though realistically unless you want to go on a holiday--or after Christmas, which COULD still be quite crowded--you can't avoid the Deluxe blockouts).
One thing that will probably be the case for some time to come is that a new attraction, coupled with a large number of passes blocking out soon thereafter, equals, well, a nightmare Fantasmic.

At least, that's what happened last time, with the new nighttime offerings. Personally, I'd expect higher crowds between 12/14 - 12/18 (lowest Southern California AP blocks out 12/17; the other's last day is 12/18) and also the week of Christmas Eve (Deluxe passes block out 12/24 through 1/2). But there could be big crowds in early December too.
If I had to guess, I would say that the August dates when the Southern California APs are usable again will be unusually busy too, with the AP holders wanting to see the Fantasmic dragon. That would start August 16th - 17th.
Sometimes you can't plan around dates you know or expect will be bad, though. The more I saw, the more horrible I thought our crowds would be (6/19 - 6/23), but I'd already asked for the time off, reserved the rooms, and I couldn't very well move the date of my birthday.

But, I found the crowds quite manageable, so I was pleasantly surprised.
