Both can be installed in SC. Pro4 is a new product series. Go for Pro4 for sure if buget is not a concern. 4000kv shall be enough for SC104x4. If you want to grap more punch, buy 4600kv. I have bought one - 4600kv for my SCTE, waiting for delivery.
Thanks for the information. Is SC4X more easy to overheat?
Can't compare at the moment since I have not tried PRO4 yet. I can assure you that there is no overheat issue for RX8 + SC4X 5.5T in SC10 4x4 even with overtray.