I think the biggest concern is not a slight temp swing but the fact that they are fairly cheaply made and could malfunction or stick in the on position causing burns to your snake. I would recommend a quality proportional tstat like a Herpstat or Helix or at the least, a quality on/off type like a Ranco or Johnson Controls. The difference is, a proportional adjusts the power to the UTH allowing for a more consistent temperature while the on/off type shuts the power to the UTH off when it gets to the correct temp. The proportionals are more expensive but better.