For a thermal rifle scope to be any good for vermin control I think it needs to have more resolution that what is currently available at the consumer end of the market, I personally wouldn't be happy with one based on the Pulsar HD or the Guide for that matter, they work very well as spotters but I would not want to shoot with one, the picture just is not clear enough when compared to tubed or digital units.
I did have a look through a very expensive military grade thermal weapons scope last year and it was very apparent that the consumer end of the market has a long way to go yet