Bought a late-model, used Orion XT8. It came with a flocked OTA, blackened secondary edges, re-worked azimuth bearings, and some age-related cosmetic spots on both mirrors. Flashlight through the back of the primary shows a number of small spots without reflectivity. The focuser is the 2" metal rack and pinion, which was a sticky mess with slop and lots of image shift. I removed the sticky stuff, replaced with white lithium grease, and re-balanced the tensioner strip and pinion box screws.
The focuser is now pretty good, no image shift and only a little lateral slop with heavier eyepieces. The images are also pretty good. Under good seeing I could focus on Jupiter at 200x sharply enough to see festoons and detailed GRS. Darkish-sky views of M51 showed some detail at 100x. Star testing shows a good pattern with very slight undercorrection.
Question is, how much improvement would there be in a more recent XT8 with a single-speed Crayford focuser, as compared to a re-worked and tuned-up 2" metal R&P? Mainly wondering about focusing ease/accuracy at high magnification, and robustness to heavy eyepieces.
More recent used XT8's come up now and then, and wondering if it would really be worth it to switch to something more recent, albeit still used.