Does the weight make your rifle 'top heavy'
I believe this is dependant on the weight of the rifle. A NF NXS on a 6-7# Remmy 700 BDL sporter.......yes, top heavy and way overboard
IMO. Also, an AR-15 type rifle, they seem top heavy to begin with. But a NF NXS on a 9 or 10 lb bolt action varmint rifle........doesn't seem top heavy at all.
With a 12 lb total weight (rifle and scope), the extra weight is more managable to carry if you get a wide elastic type sling, such as the Butler Creek Comfort Stretch or similar. It will spread the weight over more area, and each time you take a step, it will "stretch" a little and relieve the pull on your shoulder.
From a supported field position, the extra weight is actually good to have and makes the rifle easier to hold steady IMO. From an unsupported, quick field position I personally prefer a lighter scope/rifle. The buck in my signature would've never been tagged if I were shooting a heavy, hard and slow to manuver rifle that day.
In contrast, many 500+ yd coyotes would've gotten away without the extra weight and stability of the VSSF and a Nightforce scope........Not saying it couldn't have been done with a Leupold or lighter scope, but what I like about the NF's is the choice in reticles. Coyotes don't give us much time usually, and I'd rather use the time they do
give me to get the bipod legs out, read the wind and get a steady position; I use the reticle to hold over (600 or less). That way I can watch the coyote while I am getting ready. If I try and take the time to look down at a chart and then dial the knobs too, the coyote is out of sight and probably moving for too long. Leupold doesn't have the reticles that NF does.
Sorry to be so windy, but IMO it really depends on the type of shooting you're going to do, and the weight of your rifle. If you expect quick shots, possibly moving or running shots, or if you expect to have to move your shooting position frequently, then maybe NF is too heavy. If you expect to set up with a stable rest on a bipod or other support and have time to do so, the heavy rifles are great.