They both have their uses.
If you're going to use NVG's a removable is probably for you.
If you're not, the swing away magnifiers are the heat.
All in your need.
Personally, if I was dropping that kind of cash, I'd just step up and buy the one I like the best, because even at 50% off, if I decide I want the other one later, I'm going to end up spending more in the long run.
"If there must be trouble, let it be in my day, that my children may have peace"