I have similar criteria when selecting optics for any of my rifles, since at some point or another they will usually each be a travel companion into the woods, on a buggy, or in a ground blind. I was able to look through several LVPOs side by side by side during low light and dark to get a feel for which ones might have an edge. I was fortunate at the time to have quite a few different optics to look through. I have since culled down my collection to just a few scopes based mostly off of my subjective cost/weight to performance impression.
The short answer for my recommendation would be to get either the Kahles k16i or Swarovski Z6i. In my eyes they were both very noticeably ahead of the other 1-6/8s that I looked through at the time and pretty close to a larger objective scope.
The long answer is that I did a side by side in low light and after dark with a few scopes to see what I could put on a Grendel “pistol” to hunt with. I had multiple optics to look through at the time and was able to sit down and look through each during the same time. I looked through a Kahles k16i, Steiner p4xi, bushnell 1-6.5 smrs, Burris 1-8, vortex Razor 1-6, Trijicon 1-8, swaro Z6i, Leupold Mk6 1-6, bushnell Elite 3-12x44, Swarovski z3 4-12x40, Kahles 312i 3-12x50 and a Leupold vx1 3-9x40. I kept everything on 6x For the LVPOs (except the Steiner) to keep the comparisons the same.
Most of the 1-6/8s were very close. The bushnell, Leupold Mk6, Burris, and Trijicon were all very close to each other. I thought the slightly larger objective of the Trijicon would help, but it did not. The Razor was a little ahead of this group, but it was also heavier than the other 1-6s and I wasn’t a fan of how hard the mag ring is to turn. The Kahles k16i and Swarovski were better than all scopes above by a wide margin and very close to the Leupold vx1 3-9x40 (comparing low light transmission only). They were extremely impressive. It’s also worth noting that the Steiner p4xi was also very clear and bright. I was extremely impressed with the little 1-4, but the ballistic drop reticle wouldn’t work the way I wanted with the Grendel.
As you would guess, the bigger objective scopes fell in line by cost. The Leupold VX1 3-9 is good in low light. The bushnell Elite 3-12x44 was a little better (I also really liked the BTR mil reticle for hunting). Looking through both the Kahles 312i and the Swarovski z3 made things seem brighter than looking at them with my naked eye.
Due to some other projects I had going on at the time, I kept the bushnell 1-6.5 for my Grendel. It wasn’t the lightest of the bunch, nor did it have the best reticle or illumination. It is however, probably one of my favorite value LVPOs out. The reticle is designed in a way that doesn’t make its crappy illumination too much of a downside. It has good clarity and light transmission and a decently flat 1x. Whatever coating that their marketing team dubbed “rainguard” works extremely well at keeping it fog free (as seen during several cold weather hunts). The 3 I’ve owned have stood up to quite a bit of abuse. However, it is still a scope of compromises. If cost wasn’t a concern I would still have either the Z6i or the k16i. If the Burris had a mil reticle, I would probably still have it as well since I liked its turrets/illumination.
