It occurs to me that since elves and drow have natural rapier proficiency (and accompanying enhancements), that it might be a good idea for a pure or mostly-pure monk of those races to turn to a rapier when fighting high-level DPS-only bosses, such as Arraetrikos or Suulomades.
I suppose the most convincing case would be if you were a Drow. Spending 12 AP on weapon enhancements (and switching your Imp Crit feat to match) would let you TWF with 15-20/x2 and 17-20/x2 crits, instead of the 19-20/x2 gotten from Kamas. All attacks would be at +2 damage, and only a net -2 attack rolls (because being uncentered reduces from 16 to 12, but the enhancement adds +2). Activate Madstone Boots and your BAB returns to 16 regardless of weapon choice.
Alternatively, an elf monk could keep Imp Crit slash to work with kama, but equip a longsword into the mainhand for similar kinds of benefits. Dwarf monks could try it with handaxes, or monks of any race that have splashed fighter, rogue, or paladin might attempt it (but without supporting enhancements). I haven't done the math on how much DPS would be gained, or compared it with how much benefit is lost from the monk specials you can't use.
But I wonder if anyone has already tried this substitution.