I don't have my MSL/SPC code to check and see for sure on my device, but I read somewhere (can't remember where as I've been doing alot of reading) that the Epics are on EVDO Rev 0. They SHOULD be on Rev A but they're connecting at Rev 0 speeds (hence the 150k upstream limit.
Apparently Samsung is suppose to release yet another maintenance fix that will repair this 'whoops'.
I'll try to find a link for my source.
IF you guys have your MSL/SPC, check in the PST settings, or ##3282# menu and see if this is the case.
EDIT: fount the thread I was looking for.
Samsung Epic Stuck in EVDO Rel 0 - Upload cap possibly explained
Hope this helps