I haven't used that particular unit, but have used some of their other units. You can dial in the temperature you want and it will (try) to keep at that temperature. Unless your heat output is too much for the radiator and TECs to handle, it should do a good job of keeping at that temperature. That's the unique thing about their products - the TECs and the control unit.
With that being said, I probably wouldn't use one. I've already discovered their software (for the control unit) can conflict with other software in certain circumstances. Also, while it is good for locking down at a decent temperature, to do that sometimes the fan ramps up REALLY LOUD! So, good on temperature, bad on noise level. Then again,
I like my systems to be quiet.