That's a beautiful thrust bearing modification!
I already have a thrust bearing mod on mine, sold by Phenom. It is not as involved as the lovely one you showed, but it does help.
Regarding losing some Y axis, when I switched from just having the LMS Large Table to also having the Solid Column (which requires switching the base casting as well) I found that I could actually increase the Y axis travel range by spacing the front bearing block, supporting the crank end, away from the column by an extra half inch using a spacer block I made for that purpose. That almost made up for what I lost by having the DRO X axis glass scale mounted to the back of the table.
I have found with a lot of patience, trial, and error, that adjustment method you mentioned will allow me to actually tighten down the retention screw on the Y axis nut much more than the loose grip they suggest. It's a balancing act between all three screws and the angle you put on the Y axis screw by lifting or pressing down on the crank wheel while you tighten them. But eventually I find that even with the nut retention screw tightened reasonably, the nut still eventually moves, usually at the very worst possible moment while in the middle of a project, and can result in binding the screw shaft so badly you have to stop and fix it.
Rather than going the ball screw route, I am currently thinking about ways to "stabilize" the Y nut so it can move a little, but would be constrained such that it can't cock over in any direction enough to bind the screw. Perhaps a pair of springs bored one into each side, to keep it from rotating very much. I've also toyed with the idea of making a new nut with its weight mass centered at the bottom, instead of at the top. The X nut has its weight at the bottom, and it never moves on me at all. Being top heavy, the Y nut is begging to rotate all the time.
Agreed, it is a hobby level machine, but that doesn't mean it needs to be "thrown together cheaply". They've sold enough of these to have been worth more thought and a better design here. I know the X3 has a support bearing at the rear end of the Y shaft. They wouldn't have added that unless they realized it is needed, probably through complaints about the lack of it on the X2. They could have offered an X2 upgrade to add that bearing.
Creativity is how we take these "once inexpensive" (no thanks to the current establishment's tariffs) tools and make them into something truly useful. Thus the many modifications this machine has seen since I bought it years ago. This Y axis binding is pretty much the last annoyance I am trying to remove.
I Thank you all for your suggestions!