I think that my balls have NEVER burrowed, that's more a corn snake thing...but that being said, I've had both UTH and Light heat sources and haven't noticed a difference one way or another. My first ball is still in an all light heated tank and my female is in a Sterlite container with a UTH, both are happy and healthy, though controlling humidity is a lot harder with light heat sources and they break. So for aesthetics, I prefer light, for function, UTHs seem to work better.