I have one Flat Wonderful peach. It’s not recommended as a commercial variety, but truly makes a very nice backyard tree, in my location.
I’ve had this tree for about 7 years or so. It’s a consistent producer of some fruit every year. Produces beautiful lavender blossoms, and red foliage every year.
The flat fruit are enjoyable (though not the very best flat peaches). I’ve also watched an unmanaged specimen close by and it does decently for an unmanaged peach tree. This tree is a definite winner in the backyard category in the area, imo.
Here is a pic from this morning. I’ve raised over 100 different peach cultivars, and this is the only one I’ve raised which has red foliage like this early in the summer (as the summer progresses the foliage turns green like other peaches).