I had a chatty supervisor at Soarin' explain that exact thing to me while waiting in the queue at Soarin'. There's a medical grade filtration system in both projection rooms at the DCA Soarin', and they cut that from the Epcot version which allows dust and dirt and decay to infect the Epcot film prints very quickly.
The DCA version also closes each theater for a week of screen cleaning and painting once a year, plus general maintenance on the "carriages" which lift you up and into the screen to keep them from squeaking, keep the motion control in full effect, and keep the smell effects working right. The DCA rehab for Soarin' was this past January, with each theater down for a week at a time but the attraction still open. I rode the DCA Soarin' at the last AP party last week, and it looks and flies and smells
fantastic.
I can't remember the last time anyone mentioned a similar Soarin' rehab for the Epcot theaters, to clean the IMAX screens and rehab the mechanics. In addition to the superior filtration system in the projection room, the California Adventure version of Soarin' is kept in very good condition.
Just another example of the increasing differences between the two coasts and how they operate their parks. I have to wonder how much George K. will be able to help with institutional differences like that???