I've been there twice during the "Classic." I'd make the following suggestions:
#1 Don't worry about it, it just isn't that bad.
#2 Stay the hell out of MK on Saturday (this has nothing to do with the Funai, it's just a personal philosophy).
#3 Relax and don't worry about it.
Here's the deal: The crowds in Orlando WILL go up. But the traffic in the parks, from what I've seen, is affected minimally. Most people that come to this event are THERE TO SEE THE EVENT.
What it DOES mean is be glad you're on site. Use Disney transportation, this weekend more than most. The roads get massively clogged. And the on-site, out-of-park restaurants can get nusty, so don't count on any dinners without PS. And during this time, 192 (restaurants, hotels, and especially traffic) can be NUT'S.
But as for the parks? Yeah, it raises crowd levels, but hardly enough to warrant panic. If they expected New Years Eve crowds from the Funai, they'd have blacked out those dates for FTP.
Have fun!
Pat