my playgroup has made multi-shot a standard action attack.
We did this because an archer that can make a full round action with multi-shot does way too much damage but has his damage greatly limited when forced to make any movement beyond a 5 foot step.
with the change the archer can basiclly raise his standard action damage but lowers his full round action damage.
the logic being that no matter how you slice it a multi-shot takes a bit more concentration and skill. they can run 30 feet while drawing 2 arrows and relatively carefully line up the shot. but they cant just unload shots at maximum speed and throw in an extra arrow from time to time.
just posted so others can use this idea or comment on it.
Multi-shot, as its designed, is a clumsy mechanic and a definite off-note on the way combat feats are usually used.
We replaced it with a feat called 'Double Shot', made it a standard action as well... but then we also adjusted the rules for ranged attacks/round to better reflect what had already been done for two-weapon fighters.
A complete list of our changes to combat feats can be found here.