Okay, I have had a good think about this since the poll was opened. I voted "no" and that vote still stands. But, I would like to expand a bit more on why I voted no.
The first thing is the question of why Mate desktop was developed in the first place. The answer to that question is that it was developed as an antidote to Gnome 3 and Unity. In other words, Gnome 2 was a DE that was not "broken". It was, in much the same way as the classic MS DE, a fully evolved response to the needs of desktop users. Hence, the reason why, apart from having 2 panels instead of one, Gnome 2 DE is functionally very similar to Windows Classic DE - especially the cascading menu structure. This is because they both evolved to meet a fairly universal set of user environmental demands. Hardly surprising, then, that they independently co-evolved to end up as quite similar "organisms". Everything else, since MS Windows classic and Gnome 2, has been little more than reinventing the wheel. Often on the back of no-one in particular having requested that it be reinvented.
So, Mate DE, then, was and continues to be a quite deliberately designed antidote to the endless and often pointless search for novelty for often nothing other than its own sake. To that end, there is no good argument whatsoever for changing the menu that I can see, To do so is to fly directly in the face of Mate's raisin-detre.
Having said all of that, I am quite prepared to hear someone's argument for how a Pantheon menu provides more functionality than the Mate standard menu. But, I am bound to say, I will not be impressed with vague arguments that takes the form of it being more "modern".
I should make it absolutely clear, here, that I have no problem whatsoever with endless options being available and built in to the desktop such that users can, via various tweaks, end up with an environment that differs widely from the one that comes out of the box. In fact, I welcome such options. But, the one that comes out of the box should remain the classic MATE/Gnome 2 DE.