Keep in mind that if you want a TT with Gen 3 XR, it looks like they have a couple of these at $500 off:
We have a very limited supply of Model TT525P - Gen 3 XR reticle : Double Turn elevation adjustment, 0.1 mrad adj. resolution, scopes available.
armament.com
These are effectively brand new scopes with full warranty, support, etc.
Generally, between TT and ZCO, it is kind of a tough call. TT still has a small edge in image quality especially in difficult conditions and at longer distances. TT has better microcontrast and greater depth of field so I can see through mirage a little better with it. It is longer than the ZCO though.
Eyepiece on the ZCO is a little more forgiving (for the record, this has nothing to do with the 36mm tube. I do not know what "36mm viewing experience" is) and it is a really immersive view.
I prefer the elevation turret and zerostop mechanism of the TT, but locking windage of the ZCO.
If I could lego a perfect scope, I would take TT optical system and elevation turet and graft ZCO eyepiece and windage turret onto it.
As is, with a 56mm scope, I am sticking with TT, but I am really eyeing the 4-20x50 ZCO.
Reticles are in the eye of the beholder. I like both Gen 3 XR and MPCT2
ILya