From the peanut gallery, this is hilarious! nypdLieu and hgly going to the rescue of DL! Trying to show that their M fares are "comparable" to other airlines' upgradable fares after copay....
Anybody can tweak numbers and find counter example. The sad (actually, it is funny) thing is, none of them are convincing. In the best of case, DL comes in at the same price but it's the exception....
Who cares about the exception? The rule is: DL YBM fare are outrageously expensive and there is no getting around it. It's what made me leave DL.

And my experience with AA SWUs have been great! Not a single one missed, not a waitlist that has not come through! And no need to take a chance. I pay the lowest fare and in the worst case I go in Y for less than $1000. A DL M fare? So far, no one has found one under $2000 and who'd want to gamble $1000 extra when the chances of upgrades are so low.... It's mathematically unjustifiable. Just save the $1000 5 times and you can afford a paid full J ticket! Now, that's mathematically reasonable!

But I will keep throwing peanut shells to the actors! (I do eat the warm nuts AA serves me in J and F )