They are, but I doubt WT has actually sat in either seat, much less slept in one, and is probably not informed enough to make a credible judgement call either way...
I, on the other hand, spent last night in the 763 seat, and it is (still) absolute crap. I haven't flown on the new 757 yet, but a moldy Boy Scout cot would be more comfortable than the AA 763 J seat.
By comparison, flying on a LAN 763 this week into GRU, I had real lie flat (not wedgie angled flat and only if you don't have a carry-on bag) with a universal power plug and a 18" flat screen with tethered remote (as opposed to a 12V plug which you can't use if you have the portable IFE that slides into the back of the clamshell).
I could go on, but it would be like clubbing baby seals. From people who have traveled in both, the 757 appears to be a vast improvement.
And WT, AA may have taken "75% of a 757's capacity out" but they've maintained decent frequencies.
You're smart enough to know that schedule is what attracts business travelers, not the ability to be surrounded by 25-50% more flatulence.
I have it from the director level at DL that they had other plans for the shells flying to BOS and MIA, and didn't get the impression that they really cared so much about meeting AA tit for tat. They actually are under pressure to fly full planes, and this ain't gonna cut it.