Obviously I hope this thread is redundant now
, but I'd like to address a few points,
Load times with PhysFS,
On linux the difference appears to be nil.
On Windows it adds some overhead to every read operation. This overhead made it unbearable when it was first added, because Glest was reading just about everything a byte at a time. It is not slow though, its just the overhead for each call to read. We changed it all, to read as much as possible (pref. all) in one operation, and Omega's results should be reproducible on any windows, megapack in a 7z on GAE will load significantly faster than MG loading it uncompressed. (and because of the file loading changes, GAE reading it uncompressed will be even faster still).
Normal maps
So long as we use them sensibly, this should be fine. First of all it would be configurable, so people using not so good hardware can turn it off, and also we simply wouldn't use it when rendering at a distance. On buildings and other big units, when zoomed in, it would be a nice feature to have.
Specular maps
Can in some situations create a much more realistic surface (shiny stuff!), and as archmage has noted, its "cheap as chips".