The problem is this statement right here - "The only reason, in my mind for adjustables is more caster"
That is 100% false. Adjustable strut rods are not for adding caster. Period. They are to locate the LCA in such a way that there's no binding in its range of travel. Some cars may get some additional positive caster when their adjustable strut rods have been tuned to the right length, but that will depend on the car and the rest of the components used. That's very different than adjusting the strut rod length to add caster.
Next is the race car bit. Street car or race car is irrelevant for using the strut rods to add caster, it's still wrong. If anything, the race car should be even more concerned with the free movement of the suspension, which means that adjusting the length of the strut rod so that there is no binding is the most important thing. Using them to add caster could easily add binding and resistance to the travel of the LCA, which isn't good for the street or the race track. And worse for the race track (assuming your race track has corners), because you want faster transitions between the suspension being loaded one way to another. Adding binding or resistance will slow the suspensions movement from one place to another, and in the worst case situations can store energy that will unload at an inopportune time. And of course the race car should have other parts that can be used for adjusting the caster, like adjustable control arms. The SPC UCA's out there for our cars now can be used to dial in plenty of positive caster, I run my car at +6.5° and have plenty of adjustment to add more.
And then there's the heims on the street thing. The strut rods, when properly adjusted so there's no binding, are under very little load at any given time. This means they don't wear like heims in other suspension locations (ie, at the UCA). I ran QA1 style adjustable strut rods with exposed heims on my Challenger for 70k+ miles of year round street driving- rain, snow, gravel, you name it. The heims on those strut rods show very little signs of wear, and their tolerances are just fine even after all that. As I have said before, they will likely be the only part of the suspension on that car that will go back on it without some kind of update or rebuild when it goes back on the road. That same car was destroying heims at the UCA about every 7k miles, so, the exact same conditions the strut rods were exposed to. My Duster also has 30k+ miles of street driving on its adjustable struts, with no appreciable wear to the heims. And there are now boots you can put on heims like the ones used at the strut rods, so, you can keep all the road junk off of them now. There's no reason to avoid them for street use.
Same for the "harsh" thing. The strut rods shouldn't be affecting ride quality at all, especially adjustable strut rods. Keeping the LCA from flexing forward and backward under braking, acceleration and cornering shouldn't be adding any noise or jolts, they should just be holding the LCA in its proper location. If anything, when the non-adjustable OE style strut rods fully collapse their bushings they could in fact add bumps and jolts into the ride. That shouldn't so much be an issue with new bushings, but worn bushings can let stuff crash together.
This isn't my video, another member took this of his LCA and strut rod. It shows how much movement there is with the factory arrangement. This is just a drive around the block and a slow speed stop. Watch the front end of the strut rod, and how much it moves around. That's all fore/aft movement in the LCA. IMO, the adjustable strut rods are a great addition even if everything else is stock. It will reduce that caster change, making the handling much more accurate, without affecting ride quality.
Strut rod deflection
The video does a good job of showing just how much the OE strut rod bushings will deflect, not just to allow the LCA to travel up and down but how much the compress on either side with fore/aft movement of the LCA. That's all caster change. And you can pretty much eliminate all of it with adjustable strut rods with the length tuned to keep the LCA from binding.
Can you modify the factory strut rods to get them to be a proper length for your car with a little work? Sure. But why waste the effort? You will still have the fore/aft slop present because of the large rubber bushings. You may free up the suspension a little, which is a good thing, but you won't be improving the accuracy or precision of the cars handling because of the amount of caster change that the factory bushings allow under dynamic conditions.
And then there's the availability of the strut rod bushings. The 73-76 bushings are unobtanium right now. I actually just got a refund check from Summit for the set I'd had on order for the last 6+ months. So if you have a '73-76 set of strut rods, you're pretty much SOL for running stock bushings. You can use the 67-72 strut rods with the 67-72 bushings, but you'd have to locate a good set of 67-72 strut rods to do that.