The biggest problem with LPVO's IMO is the fish eye. That fucks me up far more than one having a little bit more magnification than another. I'll take a 1.5X that has a flat image over a 1.000000001x that is fish eyed any day of the week. There's more to just that though especially in FFP's, a lot of them don't get the reticle right and some of them have good a good scope with both good and bad reticle choices. CQBSS and Mark 6 are a perfect example, with the TMR-D reticle they blow since it's very hard to pick up on 1x, but with the H27D or CMR-W they're awesome.
The best LPVO I have ever looked through (sadly don't own one because I still cant justify it) is the S&B 1-8 dual CC. It appears to be 100% 1x and has a red dot in the second focal plane, and a etched reticle in the first focal plane. It's as perfect as a LPVO gets but it'll also cost you well over $3K even getting a hell of a deal on one.
Close second for me is the Leupold CQBSS H27D model. That scope is great. Flat image, a little magnification but not enough that it ever slowed me down transitioning targets over a red dot. The Leupold Mark 6 1-6 is also really great with one of the CMR reticles.
The worst two I have used for fisheye and coincidentally reticles was the NF 1-4 and NX8 1-8. The fisheye on both of these are atrocious, like I wouldn't run one if it was free bad. I tried to put up with the 1-4 for a while but couldn't. The NX8 got mounted and never even taken to the range. Whole lotta NOPE. The reticles in both also suck ass. The ATACR 1-8 is a different story, very good eyebox, very very minimal fisheye, and a usable reticle at all magnifications. IMO not as good as a CQBSS though and definitely not as good as the S&B.
Never had or used a PST 1-6 but I did have a 1-4 (two actually due to replacements) and I wouldn't buy one again. For the $400 or so it cost me, it was not the worst LPVO I've used overall. The eyebox was good, was close to 1x (not as much so as others), the glass was ok (good enough for a 4X), and the fisheye was pretty well controlled. The biggest knick from it was reliability, reliable it was not. The second was the turrets... If a LPVO has exposed turrets the windage NEEDS to be locking or very stiff (ideally capped though), and the elevation knob NEEDS to be locking or have a proper zero stop, not those shitty shims that the first gen PST's came with. The knobs on the 1-4 sucked. They were very tall and would easily snag on stuff, and were very easy to turn.
My experience with Vortex has not been very good, I have only ever had one that I have not had a problem with and that's the last one I bought which is a Razor HD-E 1-6 and that's mostly because it's been sitting new in the box for two months while I wait for my mount. I still can't personally recommend it as far as reliability or function, but a lot of people (people who use their shit) say they're the shit, and they have been awarded contracts, so there's that. My initial impressions are very good however and if it holds up then I don't think I'll have any complaints about it. Just holding it up and looking around it has a great eyebox, and the fisheye is well controlled.
Never used the Kahles but heard it's good.
As far as LPVO vs RDS.... Yes, LPVO all day every day. Only if it's a good one.
I understand not wanting to drop a lot of $$ to try out, but if you get the right deal on a used unit then you will lose less money (most likely none) if you decide to dump vs buying a cheaper one. You usually will see a CQBSS H27D pop up here or arfcom every week or two and usually around $2K with no mount or $2100-$2200 with a quality mount. I've seen several sell with Geiselle mounts in that price range, so if you buy at that price you shouldn't lose anything but shipping costs if you dump it.
Or you can call the right dealer and order a brand new Vortex Razor 1-6 for $1200 or less which is what they typically get listed used for (or more). Or you can get the new 1-10 for probably 10% off or better and as long as you get in early and for whatever reason you don't like it you should be able to dump that and not lose anything since they'll probably be backordered for the first few batches.
My $.02
