<font color=red>would I be better off going with the 25 hp Kohler or the 30 hp diesel? </font color=red>
I have the 1845, which is bigger, but am constantly impressed with the capability of the 400 series machines. As you go bigger, you get a bit higher lift and a little more power margin to swing bigger mowers, but you trade off a little maneuverability. For your size place, you certainly can use either the 1430 or the 1845. I don't think it's a question of maintenance or repair. The biggest factor is money. The diesels are more expensive and Deutz diesel mechanics aren't everywhere, but you can find them.
The 422 is a tremendous bargain right now, I think. Any repair shop that deals with commercial lawn equipment, Exmark, Gravely, Toro, etc. should be able to work on a 422 or 425. With the 425, almost any lawn equipment shop will have experience with the Kohler.
First, I'd call Power Trac and see if they can identify an owner near you. I was lucky to come across a couple near here that I could talk to, Bubenberg being one.
Then, look in the yellow pages for Robin, Kohler and Deutz engine factory designated repair shops.
For interviews, just ask if they have experience with hydraulic and hydrostatic systems. If they tell you they know everything, keep looking. If they say thay have some experience and probably can figure the systems out, you may have found the right place.
Ask if they've worked on a Power Trac. It's like the old Maytag ads, PT mechanics don't get much work, but you may find someone who has heard of the machine.
Check Dave Sisk's posts. He has an old machine, and found a place to work on it. He hasn't posted results, so maybe his experience wasn't great, but apparently the shop he found was willing to pull the engine from his and work on it without any hesitation.
Part of the fun of a Power Trac is doing this kind of information gathering. The next step is test driving. I hope you can get to Tazewell or to a PT owner and try the machines, along with testing of a lot of conventional tractors. You learn something with each test and conversation - and your money's still in the bank.
