Hi moondrop

Yes I have it on 2 live sites, each are slightly customized, and its working well in both.

Shipping costs are a poorly implemented feature in Marketplace in general, so I'd recommend spending some time (or money) getting some customization done. For the one site we have using it for physical products, I set up a product class attribute with options for different levels of shipping, and depending on your sellers these can be customized per product using regular option adjustments. This still needs a slight modification in the code so that the costs are shared appropriately. In our case the site gets no commission, the seller gets 100% of sales.

I realize its not much to go on but I've just found Marketplace to be very... rigid. You may even want to do a form alter to make sure that a paypal address is entered into a seller's account or adaptive will make noise on checkout.