Don't put the probe inside the enclosure. During feeding session, a rat chewed on the helix probe and ruined it. Because it happened on a thursday night, i couldn't get a replacement probe until the following tuesday. Good thing i had cheap ranco as a backup.
If you can afford a good proportional go ahead and get it. then pick up an on/off t-stat a reptile show or second hand as a backup. I am in michigan, so I know what its like to have fluctuating room temps.