I have used it with N-channel as a low dropout regulator. Only problem is the gate has to be about 5 volts higher than the source. I used a voltage pump to power the 723 and used about 180 ohms from the 723 output to the gate of the mosfet. In my case it was a low dropout regulator for 12V.
The in/ out differential was about .3 volts.
I think if you used a P-channel and connected the source to the regulator input, and had the drain as the output, you would not need to use a voltage pump.