I've had an MB burn up two RasPi's. Same symptoms - way too hot with way too much voltage into the Pi. I'm betting it's the square chip slightly above the mini-USB connector - RG2 - that's doing the heating up. That's the chip that got so hot on mine - so hot it heats up everything around it. Two fried PIs...
Ah yes I remember you mentioned something about this in the past. What did you end up doing? I emailed Dave to see what he can do about the board and RPi
I also lost an rpi, it was cooked dead, wont power up by any means. I had a spare pi but no spare M-board. running almost 2 days now on backup. I have reached out to MBP about this and am still waiting for response. I also have more rpi on the way, just in case.