I usually manage peaches to central leader for first 3 years and have some that I've managed this way for much longer. You need to make sure that enough sun is getting to the interior of the tree's lowest branches to keep them generating new wood- otherwise you get an unproductive and unattractive doughnut affect where lowest branches only have growth and peaches on their outer reaches. Summer pruning is helpful if not downright necessary to accomplish this where enough of the new growth in the top is removed to keep good sun reaching all of the lower branches of the tree.

I have had my first peach tree going on four years now. It produced many peaches last summer and it is trained in the open 'vase' shape. The leaves of the peach tree are really quite large and cover many of the peaches so the sun cannot reach them to help them ripen. I even removed a number of leaves this past summer to insure, high brix fruit. The 'Elberta' peaches were incredibly sweet and juicy. I started pruning the three with an open center as of its second year. It did not harm the tree at all. Peaches seem to be very fast growing. Mrs. G

Do the peaches themselves need direct sun to be sweeter, or just direct sun to the leaves which are close to the fruit and can thus "feed" the fruit? I had thought that they need sun to color (turn red), but that it was the leaves close to the fruit which make it sweet. If so, then removing leaves to ensure that the fruit colors would actually reduce their brix, unless you are removing leaves from another branch which was shading the branch with the peach in question.

I suppose one good test would be to bag the fruit in a opaque bag, preventing it from coloring. A transparent bag could be used as a control, with the brix being compared at harvest.

The leaves on the shoot holding the peaches won't generally excessively block light from reaching the peaches themselves, which is helpful for more reasons than just getting color- the sun also fights fungal disease. Most of the sugars are manufactured by nearby leaves although there is chlorophyll in the fruit also.