This discussion is very interesting, I looked to see if I could change the title to reflect the points being discussed but couldn't find a way.
Jae & Torger's diagrams and points have left me wondering why Arca haven't implemented these ideas and maths into the E-Module which would make it a very attractive purchase. Why give you a tech cam with hyperfocal distance confirmation/settings via it's E-Module without taking tilt into account during the design of this product. I imagine this may well be a future upgrade!?
Wait, hold that thought... Usable live view is around the corner!
I need to get my hands on the RM3Di to asses the pro's and con's of focusing using tilt on the ground glass. I also think Jae's use of the Disto 5 along with an app sounds interesting. It may sound like it's all a bit much but in practise I doubt it will get in the way of creativity. Knowing your focus is nailed would surely give you more creative freedom.
Each to there own I guess. Some may prefer the GG, some live view, others may prefer an app such as Jae's. Two of those are ready available, live view isn't too far way. I'm in the market now though and can't wait around for improved live view, I will consider that option when it arrives.
I haven't quite got my head around Jae's math and how I would use the Disto 5 should I decide on purchasing one vs the E-Module though. I think further explanation for my ageing grey matter is required (hint hint) :-)
In the mean time I will be trying to wrap my head around f8orbust's maths for working out tilt which I'm sure will help me understand Jae's maths as they are essentially the same thing... I know I have read this by Harold Merklinger but it was some time ago and think I need to read it again, at least for my own sanity!