Perpetual Ray doesn't come till the legs are dead, it's the tank buster after the Discoid cast that gains hits every time it's used like Akh Morn. And if it's anything like Akh Morn the savage damage will be nuts by the end of the fight. And I can confirm it is effected by Delirium Blade.

My group doesn't have a MNK currently but I would have no issues taking any of the melee they all have pros and cons, and honestly if you hate your class that much... change it.