What I like about having both is that the accurite records highs and lows, so I can be sure the temps aren't dipping too low at night. I have the flexwatt on a t-stat, so the hot spot is quite stable, but the ambient temp is somewhat more variable. And of course it measures the humidity, which the temp gun obviously does not.

The temp gun, has the advantage of being able to check several places quickly. Hot spot, cool end, somewhere in the middle, actual temp of the snake's skin, etc.

I don't keep an accurite in every enclosure, I have a few that I move around to where ever I feel I need it, like when setting up a new rack or something. But I'm really glad I have both.