I think I would probably target about 10-15% less damage than melee for phys ranged. The fact there is zero need for planning around cast times factors in and the utility would factor in more if it were actually called for more often (why is my interrupt so rarely called for anyway, it's like the whole mechanic died in SB), I don't think the party buffs phys ranged brings is a valid argument for reducing their damage much though, DRG, NIN and RPR all have party damage buffs. I'd then suggest for MCH, that if phys ranged party buffs add 10% to rdps then MCH should receive that same 10% to it's basic dps.

Really though I think they need to give us more to do rather than just more dps.