Well, I don't own one. BUT, I have very recent experience on three 5101en's that are brand new. I work for a company that manufactures orchard harvesting equipment. We also chop up the cabs on these JD tractors to make smaller fruit orchard cabs out of them. All three of these brand new tractors exhibit the same issues. Fit and finish is junk. The paint on the interior plastic trim very easily pulls off with masking tape. The subsurface of which lacks any sign of pre-painting prep. They also had numerous cross threaded or stripped out interior trim attachment screws. And not only the threads were striped out, but even the phillip's driver portions of the screws were stripped out. The majority of the glass attachment panels' hardware was loose.
And now for one of these three tractors. Just yesterday we were re-charging the A/C system and the engine idler pulley bolt sheared off. We heard a sudden change in engine RPM's and investigated finding the front accessory belt not doing anything because of the broken idler pulley bolt. Can you imagine a farmer out in his fields with a new tractor and having this happen? If they did not realize something was wrong right away this could end up in an over heated engine.
I have no experience with other brands of cabbed tractors. So I have no idea if other manufacturers have such a lousy cab assembly process of not. But given the cost of these beasts, I would be pissed if I bought a tractor that was thrown together in such a manner. Since all three of these tractors had a lot of the same issues, I have to assume the problem is endemic to JD. It definitely tells me I don't want to buy a JD tractor. I have no idea how the rest of their lines work out. B.