For the 10 bucks it will cost, the thermo is a nice addition to the temp gun. I use both, that way I can glance at the temps of my cages when I get up, go to bed, and a thousand times in between. It can be annoying to open up the cage, flip over a hide and disturb a snake to check the temps.

Having a hydrometer is always a bonus too, especially since balls are right in the middle for their needs. Doesn't hurt to be aware of what it is.