I think the dangers of a CaRX are overblown. A heater could nuke your system just as quickly as a CaRX, hence the temp probe. A CaRX has the same ability, hence the pH probes.
Tons of reefers use a heater with no issues yet a heater can warm up your tank high enough in a day to nuke everything. With a CaRX, with the effluent rates we use and the little CO2 that is used, it would take a lot to bring the alk up enough to nuke everything in a day, especially considering the range at which alk can be run, 7-11 dKh. You'd literally have to go full bore on the CO2 and liquefy all your media to the point that it would blow your system up with alk. At that point, I sure hope your pH probe is telling you something is wrong.