r0d,
The Nissan PTO's are strong and robust units. The truck that I co-drive in has one and its survived several years of our abuse with only a few problems.....which were our fault.
I've only broken the shear pin on it once, when trying to winch it up a 5-6 foot almost vertical wall......I should have put a block in it, but was running out of time.
Other time was when we used the wrong gear oil in it at a mates suggestion

. The PTO unit got too hot to touch and was spitting oil out the top of the breather, but still winched a GQ and a Rangie out of a pit once their 8274's had died. Plus we had to winch our way out of that stage afterwards. End result was a buggered worm wheel and a scuffed up worm gear. A mate is cutting a new worm wheel (brass or bronze I think?), and the gear is ok to just tidy up and re-install.
The quality of finishing of the gears is better than Toyota PTO ones, but have no idea about quality of the materials??
As for the "electric v's PTO v's hydraulic" question.....well thats up to individual preferences. I say hydraulic running off Nissan PTO, with electric back-up.
Cheers
Mitch