I was starting to render R2 when I remembered that I was able to deboss my logo onto the Unibody Coaxial Hotend and saw that there was ample flat space to add it now.

Thus, that's what I've done. I've also extended the M4 hole for the thermistor so that it's easier to tap.

What it looks like:

What it feels like (because I decided to loop EO - German (0.9x speed) while modelling after it recently popped in my mind):

Other potential enhancements

The technician sanding the milled face on emery cloth gave me an idea. I should've taken a picture, but I had put the unmilled input face against my calipers. While I could see gaps of light, the average was flat, not warped. Thus, it might be possible to manually polish the face similar to sharpening a knife:

I'm also considering adding an M3 thread in the center of the coupler plate so that a safety thermistor can be secured, though it's probably better to instead use a thermal fuse. The scewable ones only go down to 95C though:

Thus, the best solution is likely sticking a metal fuse to the plate using dual-sided 3M 468MP:

I'm also considering remaking the clamp plate out of (stainless) steel as it's 3 times as stiff as aluminium. The current plate seems a tad flexible for my tastes.