Have you guys thought of a different file format to use for composure and to render out to from Sequencer ?
Have you looked at jpeg200
http://www.fnordware.com/j2k/
shot 3 from the composure project convert to be 989megs from 10.6gigs - on lossless for the jpeg 200 it has an alpha channel and its archival level quality.
its way better than png which has a history of having issues in After Effects - and its 1/5-1/10 the size of an exr. Plus they are not playing back in real time on my machine and i have a new 7700chip- 64gigs of ram and dual 1080’s