Barehunter, we have a FLIR T320, they don't market it anymore, but think it is still sold. We use it for thermal studies on bats and we have used it for inspections and you can find gaps and things you wouldn't see otherwise.
However......
Before you spend your cash, realize FLIR is great but in attic temps mid day or in a field for example in a hot part of the year, critters will look like rocks or drywall, or metal. The folks at FLIR have asked us for pics and video a few times and frankly I can't provide them anything that most guys would relate to.
Can you see heat through the wall, yes you can if the conditions are right, but that really depends on the time of day, the heat of the animal you are after, some folks use them for finding bee swarms in walls (maybe not the right term, David can correct me on that).
When we first tested one, we put a small 2 gallon bucket of warm water up in our garage attic, on the insulation and within 15 minutes could see the circle from the bottom of the bucket, neat little gizmo.
However at $1,595, I might see the need or use, but remember it depends on your environment and in GA you might have more season where it wouldn't help than the winter months when it might shine when diff. in ambient heat and critter are more clear.
I hope that helps, I like electronics so don't want to defeat your interest, but need to know you may find more or less use for it than I do. I use it only on studies now and it is right at home doing what we do, but know folks who have bought them and regret the purchase.
Not sure if the I5 connects to the ipad through bluetooth, but if so, this can shine for folks wanting to show the client some views inside their attic while the tech crawls around, etc...
No one can say not to buy it, but keep these things in mind and hope they help.
Justin