IT is just such a common misconception that scopes and binoculars actually do "gather" light that I have to respond to it when I see it. I wish I had an opinion for you on those scopes but have never used or owned a Burris Full Field or FF2 either. I did own a Signature 2-8 but didn't care for it and sold it off cheap and replaced it with a Bushnell Elite 3200 2-7. I'm much happier now.
I will say what I've often said here and in other places. You just plain don't need a scope with an objective of over 40mm or with a power over 9X at the upper end for any legal big game hunting in the US. Hogs in TX or predators at night where legal maybe but even then I honestly don't think so. In both situations you can and normally will either hunt on well moon lit nights or use artifical light for the shot. Given that a quality scope with multi coated optics and a 40MM or so objective and a magnification range of 2-7, 2.5-8 or 3-9 is all that is needed for ethical shooting during legal shooting hours.