I have the same question.
Comments, anyone?
Like I said, I don’t have much time with my 5-27, so take this with a grain of salt. My 4-20 is the sole optic that I’ve owned that I like more over time. I haven’t “had them all”, but compared to Tangent Theta, Kahles, ATACR, AMG, G2R, Mk5, and some others, the 4-20 is just outstanding by comparison.
There is of course hyperbole thrown out with many of these high end optics reviews. But for the most part, what has been said about the 4-20 holds true.
I’m not a mag whore, and the 4-20 does everything I want it to do. I have a hard time imagining that the 5-27 will really out perform the 4-20 in many (or any) area, but time will tell. Controls are the same, “image” is the same, I can’t tell a difference in FoV, eyebox seems same or similar, etc. the 56mm objective should help more in low light, but I’ve yet to have the slightest issue with the 4-20’s 50mm objective.
For me, the 4-20 represents the best do-everything package that I’ve owned. The downfalls are weight, and I would prefer a longer optic (but I’m sure I’m the minority there). If ZCO came out with a 26oz 420H, I’d sell my tangent and the 5-27 to pick up a couple of ‘H’ models.
As I mentioned above, the Tangent falls just behind the ZCO overall, followed by Kahles. Then below that is a separate tier with ATACR, G2R, etc. IMO.