I don't think you're going to get nearly that throughput on a real backup, Brad, and from all reports the vast majority of eSATA drives/controllers do not support startup.
I've found TM backups over wireless to be extremely slow, but my configuration (which includes some large email folders, which change regularly, which is a pathological case for TM -- it performs *terribly* with big folders that have one or two changes) might be unusual.
I'm sure you can configure TM to skip files, but I'm really not in a position to provide Time Machine support. It's best to direct those kinds of things to Apple.
