Im currently trying to decide between a trail 38 and the newer thermion 38. Ive been using a sightmark NV 4.6x. Not sure between the 2.2x or the 4x of the thermion.
I'm a low magnification, wide FOV advocate and I agree with PigPopper that something in the 2x range is a real sweet spot. However, I sell a whole lot of 4x scopes to hunters who can't imagine using any less base mag. It really comes down to your hunting style and person preferences.
In my opinion, if you're taking a lot of shots under 75-100 yards, 4x is a little too much magnification. I would definitely lean towards a 1.5-2.5x base mag for lots of shots under 75 yards. On the other hand, there are thousands upon thousands of hunters using the Sightmark Photons, Wraiths, NVRS, ATN X-Sights etc and they are almost all 4x+ magnification. The point I'm making is, it's definitely possible to use higher magnification for closer shots but the lower mag and wider FOV is a benefit at close ranges.
I think in a situation like this, you have an advantage because you've been using the 4x NVRS so you know what works for you. Is 4x ok? If so, the XM38 is a great choice. If you really feel like sometimes you're squeezed and wish for less magnification, I'd consider the XQ38 or XQ50.
Hope that helps.
Jason