Interesting postings and fun to play with the math, IMO.
When i 1st started playing around with the MD for rangefinding, i kept seeing this 27.78 factor, and couldn't figure out where it came from. When i found out it was just the range of subtension measurement to subtension itself (100/3.6) that turned on a light bulb in my head (dim though it may be). I thought to myself why couldn't it be used with any subtension, like a plex reticle, or ballistic reticle like Burris's Ballistic Plex. Well turns out it does work, just fine, sometimes even more accurately than the milliradian itself.
Several years ago my buddy was using his VX-III 4.5-14x with plex reticle for his coyote rig. We were taking a break one afternoon and a herd of antelope came by. I told him to bracket the buck in it, and tell me what the reading was. He ranged at ~500 lasered. He said it occupied 110% x-hair to plex post tip (2.7 inch per hundred yds. which is the std. for many of the VX-III models). So i punched it into the most basic form of the mil-ranging formula figuring 15" back to brisket (avg. buck)--
15 x 100 / 2.7 / 1.1 = 505 yds.
They made their way out to ~700 lasered so i told him to do it again, and he got 80% (0.8)--
This was really a huge epiphany for me when i found out that the mil-ranging formula wasn't specific to the mil-dot reticle, and opened up a door that is way bigger than mil-ranging with the MD reticle alone.
Another important aspect of "mil-ranging" with the mil-ranging formula is that it also defines downrange zeroing with any reticle or turret system as well, since if u think about it a bullet drop referenced through an optic is the same sort of measurment as a tgt. size. Suppose u want to know how many MOA to put into your scope for 54" drop at 633 yds.--
54 x 100 / 1.047 / x = 633
IMO, once the shooter has a complete understanding of the MR formula and the inversely proportional nature of magnification vs. subtension in 2FP reticles a world is opened up to the shooter comparable to what reloading does for the shooter.