Hello Robert,
First let me commend Doug's use of the term "elegant." Its very apropos! The digital-line of modern view-cameras employs existing technology for movements, but adds micrometer-scale adjustment. That's nice...of course!
But...having said that, let me address plane-of-focus first. On my P2 I use an optical eyepiece that allows me to view each portion of the image just like a regular free-hand eyepiece....mm-by-mm. Of course my viewing area is 1:3.47 smaller than 4x5, so Robert your ability to live-view will assist where my tired eyes fail.
One thing I have learned is that my rear-movements can aid the depth-of-field, if I am very careful about the geometry...emphasis on "careful."
The overall depth-of-field (however achieved) greatly enhances the impact of the final image when recorded on the digital sensor. With film we had the thickness of the emulsion (16-18 microns for negative film, 25-27 microns for transparencies, 7-10 microns for B&W) to expose for peak focus, whereas with a digital sensor we have 1-7 microns (photosite depth, not width). Width varies greatly by manufacturer. So, in my direct experience there's at least a 3x greater sensitivity in focusing for digital.
Using live-view leaps all of those limitations easily.
Now to address sliding-backs. With the P3 (and similar cameras) the sliding back is limited by the cross-sectional area of the bellows. With the P2 I get to move my sensor up-down-sideways within the lens- IC to create a composition that not only pleases me, but expands my possibilities for stitching, etc. So, there is a distinct advantage to the larger bellows cross-sectional area.
Now......I'm not sure if this adequately addresses all your questions, but I hope it continues to carry your exploration further toward your goals.
Cheers,
Hank