31 pto hp. If I did 5 stumps a week that would be a lot. I may do no stumps a month. Need something to test the water
The key to making money with a PTO stumpgrinder, is by marketing towards jobs that have numerous stumps to grind such as small scale clearing cleanup. I wouldn't bother marketing towards single stump grinding jobs as it's really not worth your time (and the dedicated machines are much better for this)
When you figure you have to hook up the grinder, load the trailer, drive there, unload, grind, load up, drive home, unload etc, it's just not worth it. You might make maybe 120 bucks on a decent sized stump, unless it's a giant 4' stump or so and you could charge more, but the majority are smaller.
So since the way to make money with these is multi stump jobs, you want something that lends itself to that, which with 31 hp your obviously limited, but I'd recommend looking for a used Woods TSG 50 or Shaver SC 25.
If your just doing your own stumps then this seems like a good cost effective value priced grinder that will work, especially with level ground and an HST TRANSMISSION, but if you have any incentive to do commercial work with it then you would be better off in the long run with a more commercial style offering.
If I hired someone to grind a stump for me and they showed up with this grinder, I'd be less than impressed.
On top of that, the resale on the woodland mills is going to be very low, whereas the woods and shaver models hold they're value quite well, which is certainly something to consider, when your looking at overall cost of ownership.
For instance, I could sell my grinder now for more than I paid for it, yet it's already made me back more money than it would have cost me new.
Just something to think about.