Long overdue but I just got around to testing the module. I tried two scenarios both with successful outcomes.

1. Buyer buys from seller
Result: the commission for the sale set in marketplace was sent directly to the seller and the remainder deposited in the ubercart store owner's paypal account

1. Buy buys from 2 sellers simultaneously
Result: the commission was sent directly to both sellers and the remainder deposited to the ubercart store owner

I don't have any shippable goods so the rest doesn't seem to apply to me.

Thanks again for all your work Dave the Brave!