I'd love to see one of these alternate auction sites actively COURT a valuable resource like Auctiva. That alone would get my attention as a seller, that the other site has a working knowledge of what would be important to ME as a seller.
I understand that integrating the format is time and resource expensive for Auctiva...but if another auction site REALLY wants to compete with ebay, they'd be hanging like a VULTURE trying to figure out how to get us sellers to migrate en-masse...hint to them: make YOUR auction site directly compatible for Auctiva! Then, with the click of a button (conceivably) we sellers could CHOOSE which site our just-loaded-auction would land upon.
I only just wish I knew who and where, to suggest this. I personally would LOVE the final outcome of that wonderful world of CHOICE.