I try to keep my peach trees at 8'. I know that's not as majestic as a 14 footer. But for my eye, they can still look pretty cool because they are very spreading.
There's a relatively new grower about 30 mi. from me and he put in a high density apple orchard like you mentioned. It's now working really well for him. He does have to irrigate, and trellis the trees of course, but he gets good production. I'm sure your orchard will come around and you'll be in 50,000 lbs./acre club (i.e. 1000 bu/ac).
If you want to see some pics of his trellised apples, here is his Facebook page. He has peaches and blackberries too. Super nice guy.
I've heard of 1000 bu/ac peaches too, but it's not for me. My peaches at the farm are about like yours with a little more space between the rows (18X25). I did 18 foot within the row spacing because that's plenty of room, as you don't have any equipment in between the trees within the rows. I spaced the rows 25' because my trees at the house would have a 20' spread if I let them. That only leaves 5' to drive a tractor down the rows, so I figure I'll still have to prune laterals a bit to keep from hitting them with the tractor, as the trees age.
Most people around here space rows about 20' apart like you.