I picked up a Mk5 prior to the announcement of the new NX8. The Mk5 has nice turrets (crisp adjustments, capped windage, locking elevation, revolution indicators), is pretty light, and surprisingly bright to my eyes.
The 35mm tube is dumb to me, and limits mounting options. Leupold's cost increase for illumination is crazy, but I picked up a new non-illuminated for ~$1,450, which is substantially less than the NX8.
The parallax is finicky to me on the Mk5, but I would guess DoF will be similar on the NX8, just based on geometry (I'm no expert).
I've read several say that the NX8 turrets are on the mushy end, relatively speaking, but can't say from first hand.
Reticles are personal and not really worth trying to compare between us.
In the end, I think we're just lucky to have sooo many great choices in optics nowadays. Let us know what you decide.