I'm looking into the spec of some GaN transistor and they look much better than normal MOSFET , for example this http://www.gansystems.com/datasheets/20150904/GS61008T%20DS%20Rev%20150904.pdf transistor is a 100 V 7,4 mOhm and is only 3mm x 6 mm big and is rated for a peak current of 90Ampere , I think current controller can become less than one quarter in size compared to current mosfet controller for the same current. Also SiC components looks very good and in both cases the price very close to the standard silicon part