Also, I thought I remembered hearing last night that the UMO upgrade (with the heated bed, new z-stage, and hot end fan enclosure) includes a new PSU, and that some basic wire stripping / soldering may be required to piggyback/power the new mini heater electronics board via the UM electronics.
This would only potentially work on an upgraded UMO since it has the two separate electronics boards, but couldn't you, in theory, use the new PSU and dedicate it to the heater board and leave the original PSU connected to the UMO electronics? You would have to plug in two PSUs but then wouldn't have a wattage issue.
Note: I haven't seen the actual kit - last night's demo was using the UMO+ with the UM2 electronics, so all of this is speculation on my part.