Mike,
You are confusing the visual resolution with thermal resolution. As Anatol pointed out the thermal resolution is 80x60 which is 4800 pixels. While you can use this, the resolution is pretty low. Once you have a higher resolution camera in your hand it would be tough to use this for anything other than a glorified temperature gun. It might fit what you are needing but if advancing in thermography at all it does not even start. In your post you do say you use it only for radiant heat which it would work for. One of the things I do not like is it clips onto the phone and we already have enough trouble with the jacks on the phones going bad, this only adds to the problem. You might consider the C5 as an alternative, More durable and stand alone, yes more money but no wear on your phone jack. I have one for just the purpose of accurate temperature readings on the surfaces of the materials I am looking at. I do a lot off building diagnostics and forensics and do not enjoy carrying my T540 in attics just to get a temp on the building materials. The T540 is my fifth camera and I do want to msake it lasts at least one more year. At 15K I like to get at least 4 years out of it.