The commander pro comes with its own probes, additionally if you buy the XD5 or XD7 reservoirs, they come with a probe fitted to a G1/4 so you can probe coolant temperature.
I already have such a coolant probe in my loop, and would prefer to not open the loop (which, btw., is practically a as close to AIO as a custom loop can be while being worth the hassle of a custom loop).