Personally I don't treat my tractor like a baby. If there is something that a reasonable person should be able to do with a reasonably built tractor, I do it.
If I had a 3 PT PTO winch, I probably would not hesitate to use it.
I don't have the upgraded CAMs. If I could have gotten them upgraded without a hassle then I would have. That said, I'm not going to treat my PTO like it wasn't meant to be used.
I do the sensible thing and avoid letting it rachet when disengaging it, knowing that anything that rachets will eventually wear down.
If the PTO breaks, I will get it fixed. I have another 1 1/4 years of warranty. If it breaks after that, I will pay for it and I will chalk it up to the cost of owning and using machinery and a bit of bad luck.
There is no question that there were some failures on the PTO and along with the racheting noise that was good reason for Kubota to upgrade the CAM design. That said, its not like the original PTO cams are likely to self destruct if you happen to use the PTO either. There were one or two threads at most that reported a PTO failure. That does not sound like it was widespread or had a long history of problems.
Kubota has sold a lot of L3400s that are probably being used in ways that you are I cannot think of, and are generally holding up fine.
If you are still in doubt, go ahead and add an external over running coupler to ensure that the PTO cannot ever be powered by the implement.