ASV.
This has been touched on before.
You need to define a mission.
Looking for ‘hot-spots’ in overhead cables is somewhat different to the mission where you might want to find a running man in a pursuit. There are a number of other potential scenarios - there is a World of difference between a hand held FLIR in the back streets of some southern US state and say the unit on any military EH101 .
In a low use wire survey role you might be happy with a fixed or hand held uncooled unit. Cost effectiveness will matter and as a result you may not need to buy from a large supplier. If you live ‘down the road’ from a factory of an ‘unknown’ manufacturer it might make more sense to go to them that to go to one of the big manufacturers over 1,000 miles way.
If you are thinking pursuit you need to consider where you intend to fly. If you are in the USA you can buy low-cost units that is fine being flown very visibly at 300-500 feet but pretty lame when operating at 1,000 feet. If you are in Europe you will naturally go for a higher spec unit that allows you to do the job covertly from more than 1,000 feet.
In the end its probably a compromise that the Buck will decide.
More input required!