I just got my 12" with Rumba board up and running and haven't had any issues. I chose the Rumba over RAMPS for the updated design, replaceable stepper drivers, and the ability to use up to three extruders with the rumba out of the box (thinking down the line for upgrades).

I have not done much research with ABL for the Rumba but I know some folks have it running so it's possible.

Also, the 12" comes with a relay to power the heated bed so you wire directly to the relay then to the bed from your power supply.