mark got it right ... my problem with the pulsars ... and most of the non-military thermal clipons is they really aren't clipons, they don't have risley prism or equivalent collminating lenses on the back end. So you have to "adjust" them for every rifle/scope combination.
Also, most of the commercial clipons only support about 3x to 5x on the magnification on the day scope. I want more !
The only commercial thermal clipon I would want to buy is the SNIPE and even though it does have risley prism or equivalent back end ... at least on the one I had, they skipped a step. They forgot to put it on a collimating table! Soooo, you still have to adjust it for every rifle/scope combination. But it can get up to 7x with a decent image. I pushed it to 8x
If you want a low cost solution for hog / yote hunting ... and 3x to 5x works for you ... then the pulsars will work. If you want 10x or above on the day scope, then the pulsars are not even in the ball park. If you go that way, then your issue will be mounting. You can mount them on the objective bell of the day scope, but in my experience that doesn't work too well. It will work for a 5.56 or below ... but when I've tried on a .308 the mount kept coming loose. I tried to tighten it down more and broke it. So, a rail mount is preferred. But then that might cause you to need to change your scope mount depending on how close you are on center height alignment.
And then you must realize, you are "zooming in on the TV". So at 2x you will loose 75% of your pixels ... and at 4x you will loose another 75% of your pixels. And arguably "pixel count = resolution". With a dedicated thermal scope, your magnification is on the front end ... 2x .. or 3x ... no resolution loss. You only loose resolution on the dedicated scopes, when you click on the "digital zoom". Then the same rule, 2x loose 75% of the resolution, 4x another 75% otherwise known as 94% of your resolution lost for 4x. With a dedicated thermal scope, you can get 2x or 3x or 4x lens on the front and loose no resolution for that front end magnification. That will give you a good image with some magnification, depending on how far out you are shooting or scanning.
So, for the VAST majority of hunters, I recommend dedicated scopes for thermals and if you really need to shoot long distance with thermal, then I recommend those military thermal clipons specifically designed as long distance clipons, like the FLIR T-75 or the BAE UTC-x.