The rabbit tail is only useful if not relying on melees to do your damage, or if you pop it as a last resort to cure bomb everyone back to full, or let the mages rest. If you're using melees to do damage and you pop a tail, you've lost most of your damage during that time from chasing him around.
If you were relying on PD HF and you use a tail, you've lost.
Also, I'm quite surprised at just how many people are struggling to find this 1337 setup of monks and a PD smn, considering that abyssea means most people have lots of different jobs levelled.
Admittedly, some 95 mnks don't have asuran, as they leeched to cap, then got their LS to get them a Vere, so it was never an issue, and not all smn bothered to get alex yet even though he has been around for a while.
However, I went in for a 2nd run to help a friend and we got 3 mnks, rdm smn and me. I was going to go as thf (you only need 3 mnks to win if they're half-decent) since my mnk isn't well geared, and at 95 only had ~320 H2H skill. It turned out though that 2 mnks were only 91, and the 95 monk didn't have asuran and was all in pink, so I went on mnk too after killing a mob to put me at 96.
My level 91 mnk friend pulled hate from me about half way through the fight as he was much better geared than I was, also I lost some of my HF time because the rdm cast enfeeble right at start and pulled hate as we were about to hit him, so we had to chase him for a couple of seconds.
Anyway, we won with some gimped people so just goes to show that as long as you get an alex smn, any mnks will do for this. Just don't wear your haste gear during HF FFS, unless it's also the best acc gear you have too. (I had 7% haste equipped >.>)