After reading this thread for quite a while, the only input I have in regards to Dynamis, is that I personally stopped caring about it a long time ago. It's three hours I have to be at my computer, paying attention, without much of a chance for AFK's. Anymore, that's hard for me to do for that long. I get distracted, play with the dog, write, exercise, or just watch TV. Some of the time I'll leave FFXI on when I go do other stuff.
Case in point, it may only be losing steam, not because of being horrendously boring (I personally enjoyed it while I could stand it), but because of the amount of time required to focus, and plan ahead of time. I mean, you have to wait for everyone to show, another 30 to enter, and then you start. While some people may still enjoy the hell out of it, some just don't anymore, and I fall in that crowd. Einherjar, Limbus, and Salvage are freakin perfect for small, organized events that take very little time in comparison to the requirements of Dynamis.
Otherwise, there are some nice things to be gained from it, naturally, like all endgame things. My 2 cents. Yours may vary.