Fraser,
Thanks for the update. I also have some high resolution imagery that i have turned into a basemap. 3 inch resolution for 580 square miles that have been combined into a FGDB raster dataset that is now 897GB Uncompressed size, but is 327 GB on disk.
When you say too inconvienient to cache, not sure if you mean that you don't have the storage for this, or the CPU time to spend on it?
I ended up caching my imagery dataset, though it took one of my "lesser" computers 6 days to do it. I cached in the "old" Exploded format, and the total cache is only 84 GB, but what a huge increase in performance. No longer have to load my "good" imagery as dynamic.
R_