someone once asked me - do you buy a pair of pants with your suit and not get them tailored?
it sounds like you are comfortable with your swing. a fitting will only help that. most beginner golfers probably shouldnt get fitted as they are changing their swing so frequently, inconsistent swing path, etc. for a more veteran golfer, i would definitely recommend it. i have had one set of fitted irons and they were like heaven. they have you hit in front of a swing monitor and measure trajectory, spin, ball flight, velocity, etc. from this the data they change a few things on the club from weighting to actual changing of the lie angle. they will change the club to fit your swing so you are hitting the ball in the right spot every time. i would not recommend dicks though. especially not at one of their larger stores. the people there just arent trained well enough to make it worthwhile (at least at the location i was at). i walked out on a fitting there and have been looking for a shop around to go to. ask your pro at the club for recommendations, im sure they know someone.
and getting back to normal, you shouldnt notice that big of a difference. subtleties in ball flight, etc. where you may have had an iron that was consistently leaking out you will start to hit the ball flight you want.