My Kahles 624i is a beast, and still running strong and tracking perfectly after seven or eight years and many barrels. I honestly never noticed the chromatic aberation till SH freaked out about it. A slight purple tinge has never bothered me one bit, and I didn't even see it till the panic of 2016 (or whatever). Still shooting it, and would consider another, but very happy with the ZCOs as well.
I think it's funny some people don't think Kahles is "tier one". Totally is. Maybe TT and ZCO are a little better, but a Kahles isn't going to hold back your shooting one iota, and it has features that are great. People are always saying "left windage", but it's that the parallax is on the right that's so convenient so your support hand can stay on the front stock (limb) while you're getting the target sharp.
Can't go wrong with either, and rather than go to some store/warehouse, go to a match, and anyone will let you look through/fingerbang their scope and rifle. We're kewl like that.