Even though I (briefly) majored in EE in college, my credentials do not meet your stringent criteria. I ended up as a computer magazine editor!

The usual recommendation is that if you must lengthen wires, it's better to lengthen the ESC-to-motor wires rather than the ESC-to-battery wires. This is what several ESC manufacturers and vendors recommend.

Here is an thread where the technical reasons are debated:
[link=http://www.rcgroups.com/forums/showthread.php?t=952523]Careful! - long battery wires will kill ESC[/link]

There are plenty of links in the thread, so you can spend an hour or so reading everything and then draw your own conclusions.

- Jeff