Mitch,
You are entering the no free lunch zone.
You have potentially 3 choices going with adjustable strut rods:
1) adjustable struts w/ rubber bushings
2) adjustable struts w/ poly bushings
3) adjustable struts w/ no bushing & using a heim joint.
1) the rubber will flex and negate some of the effects of the adjustable strut. As such, you'll adjust more to compensate for the flex. Part of the reason your rubber bushings have lasted so long (besides the limited use) is the fact that they were working with the factory strut rod. Using an adjustable will introduce preload into the bushing and make it flex more than it used to. That will undoubtedly increase bushing wear, but without empirical evidence, this is still just theory in my head.
2) the poly flexes less and in my experiences poly has a shorter life compared to rubber in the same environments, but it does firm up stuff some.
3) This style actually keeps the most consistent suspension geometry as everything is a hard point with a pivot. Heim joints will actually free up the bushing bind as the LCA travels in its arc. Uncovered heim joints require inspection. They are like a ball joint. Precision fit, but a small amount of dirt can make them crap in short order. The position of the forward heim really won't get much dirt kick up like an UCA with a heim. Put a boot on it and treat it like a sealed ball joint. Just give it a good dose of dry lubricant before you put the boot on. This style of strut rod will put the tension load on the K-frame. A reinforced k-frame won't care. Non-reinforced its not much of an issue, either. HOWEVER an accident with an impact to the front wheel may incur more damage as the load path from the strike won't terminate in a bushing (that's why factory style tie rods are cheap and hollow, they are the first sacrificial part in that scenario).
My personal choice is #3. I'm just trying to keep the car pointed the right way now.
(sorry for the long post)
You covered a lot pertinent ground, but you have not mentioned that a rigid pivot strut rod, induces a small arc in the LCA as it moves up and down. The OEM allows for this by using rubber I suspect. Almost all other LCA bushings, I suspect even the delrin bushing will allow that small motion. If that arc was resisted, you would have bind. Granted the induced arc is minor, but then those who are making this upgrade "think" they are reducing unwanted movement in the first place. I suspect the LCA might even flex in this new arc induced by a rigid strut rod mounting, since the LCA main strength is vertical by its greater height cross section. Of course those that add the lower rein forcing plate would reduce this flex, and therefore drift closer to bind, not a wanted outcome. All this means to me going full circle, not sure why bother with the upgrade if the installed rubber bushings are in good shape and tight, for anything short of Nascar
use.
For discussion sake, is there consensus the strut's biggest and most important loading is when under braking?
