I'll have to respond to some of the items posted here later, but I wanted to point those who are interested to a new thread in the Balance Mod forums at SE.net:
http://www.spaceempires.net/home/ftopict-2115.html
It's a proposal for a change to the Engine system. There's not much change to the actual mechanics really, but I think it restores some strategy back to engine usage that was sort of lost with the current Balance Mod engine system.