dont really have any proper testing to back up my anecdotal observations, but I havent had any hangs on the bbblack, which I cant claim the same for the Rpi (I do have a R1 tho, cant speak to the R2)
Less usb and eth issues with the bbblack personally. again, opinionated observation would lead me to the whole phy eth chip on bbblack vs usb based eth on rpi.
1ghz vs 700mhz cpu, while not frequently an issue, could be if more stuff is added to the webui, demanding more processing for display.
Memory's the same between a bbblack and R2 rpi.
The onboard eMMC is useful, being that you can install the os to it and then be able to make use of the sd slot.
rpi powered by usb connection. bbb has barrel jack or usb powered.
rpi has 2 usb ports, bbb just one, so if youre not using a hub, this could be an issue.
the novelty of block erupters stacked on it as capes would be fun, but still, just a novelty.
all in all, no 'direct' benefit of a port, imo. would just be a potential interesting alternative that's still in the cheap little system board category.
definitely keeping the donation idea in the back of my head
*keeps an eye on current coins earned from my running minepeon setup*