Peach trees, almost all are grafted because most peach tree varieties (cultivars) are very disease prone. The understock they are grafted to can be peach, apricot or plum. So by chopping below the graft will leave you with a fruit tree, but no guarantee as to what type it is unless that nursery tag mentions the type of understock.
I have enough trouble keeping a landscape peach tree healthy, I am certain as bonsai it would be even more problematic. This is the reason you don't see them often as bonsai. Otherwise my guess they would take to bonsai techniques about as well as Ume. Imagine an Ume with larger leaves and slightly more coarse branch structure. Best for medium to large size bonsai, if you have the right climate where disease issues are not a problem.
At the group owned ''family farm'', the farm is in the commercial peach growing area. I haven't tried any peaches there yet as we only picked up the property end of 2015. If I were to do it again, I would air layer the peach cultivar off its unterstock. And then try to use the air layer as my bonsai. This way it will be true to type.. The flowers of peach are a wonderful pink, and different than Ume or any of the others.
Apricots, the culinary fruit, not ume, are much more disease resistant than peaches, and are moderately common as ''own root'' trees, not just grafted trees. The apricots bloom just ahead of the peaches. Fruit of apricot is smaller, more in scale for a bonsai than a peach would be, should you choose to let the fruit develop. Some of the flowering plums have flower colors similar to peach, if the flower color was the reason you wanted a peach bonsai.
One can also plant peach pits, my understanding is they only take 5 to 8 years from seed to start blooming. They bloom from seed much quicker than apples, which can take up to 15 to 25 years to bloom from seed. This is one way to get peaches without graft scars on the trunk.