I knew it. Page 3. Here we are.
I honestly don't think that Empire need an overhaul, or even that much tweaking. We all know that some aspects of the army don't compete as well, and all want fixes for the engineer, Halberds, and GotE. But other than that, the army works just fine.
Moving anything to core would be overpowering. Can you imagine if a cannon or unit of Greatswords were core? The army would get cheezy very fast. It's bad enough with flagellants, and people only accept one of them as Core because they die so easily. Empire could field 5 Cannons!
State troops - meh. They need no reworking (excepting the aforementioned Halberds). Stick a character in the unit and it is usually okay until the character dies or something else hits it.
The one idea I have read that I really liked was one of Warlord's in which the general had an 'Elector Count' upgrade, where he got a runefang for 100 extra points, but could only take 50 pts of magic items. 18" Ld. radius, while nice, does not fit the fluff at all. Empire does not have inspiring leaders more so than any other race (or in this case more audible), with the obvious exception of our special characters.