I think what you fail to realise is that the sparkfun board will create SIGNALS that can used with higher voltage logic. This is NOT a driver board and it will fail to provide much of anything in the way of high side "current". You CAN use this board to drive higher voltage rated MOSFETS. You should consider that.
So... the board outputs SIGNALS of GND and HV Voltage to be further used as needed to "drive" your loads with "something" suited to "driving loads".
Think of it more like an optically isolated level converter.