It turned out great. I was really bumbed out at the end of the keg. Really drinkable. I'd be interested to know how it turns out with pears. My back yard has a plum tree so I think I might give it a whirl with those.
Keep a few things in mind though. The sugar content of peaches and pears are probably a lot different so you could end up with a less, or more alcoholic beer. Also the use of the under riped peaches added some nice tartness. I don't know how much of that you'd get from under ripe pears.