Hi Brian,
I work with one of my clients regularly on ultra-widescreen projects around 13,000 x 1,200 pixels -- 15.5 megapixels, or about 7.5 times bigger than a single HD frame. Render time is often measured in days instead of hours, and sometimes becomes a design constraint.
Because of this, After Effects workflow, performance, and network rendering issues are really important for me. I share your excitement about the 64-bit version!
I should add that moving to an 8-core workstation with 32GB of RAM made a world of difference to me over my prior dual-core system -- I imagine you would see a huge boost as well.
Walter Soyka, Principal
Keen Live, Inc.
Presentation, Motion Graphics & Widescreen Design
RenderBreak: A Blog on Innovation in Production