First advice is don't do it.... unless you are willing to close out your retirement.... And send your kids too community college
I had both a fxq50 and a trail XP50 if those
you listed are seriously the choices on your list then get the thermion! 384 vs 640 for starters, plus the comments about not getting a clip-on unless you ready to close that retirement account.... I personally don't care for the extra weight so I'm all about lighter guns and lighter optics which a clip-on does NOT go with. But I'm also not even about to try and shoot 7-800 yards which some of these guys with the high end clip-on units are pushing it on out there
Fov is very important for scanning, but I like magnification for my scope... Just plan on getting to seperate items eventually. Because you'll either try it and never really get going, and sell it... Or like Horta said, it'll be cheaper to try meth prolly