There is a semi-solution to the importing feedback problem. You can go to FeedBackSite.com and sign up all your online auction accounts through them. You can then place their code at the bottom of all your auctions (or tell sellers to look at the code) so everyone will know that you have high ratings elsewhere. It's not the best but it does help. I know I'm far more willing to buy from a person that might have only a one or a two on Bidville but has a feedback of over 200+ over on ebay.
The feedback site does require verification so it's pretty hard to scam someone into just thinking you have a high feedback elsewhere..