I'm a big IK guy. I like IK, I like working with it, and hate the counter-animation that I feel I have to do if I try to use FK for the arms.
Yeah, yeah - I know, I know. Everyone likes FK for the arms. Good for you. Maybe someday I'll join your FK cult, but for now, I'm an IK guy. :)
So, how do you use IK without letting them LOOK IK?
Well, as far as I'm concerned, you've hopefully done some planning and know what your poses are going to be on what frames, at least generally speaking. If that's the case, then you're just going to a frame, sculpting your pose, and then saving a key on everything, and then moving on to do the same thing a few frames later or whatever, right?
Hopefully, that is the way you are working. If you are only in the first five or six years of being an animator or are a student, then I strongly believe you SHOULD be working that way.
So, if that's the case, then sculpting a pose with IK arms should look exactly the same as sculpting it with FK arms, right? As long as you are carefully crafting your breakdown poses to control the arcs of the arms, the overlap and follow-through, etc, -- then the IK and FK versions of the shot look look EXACTLY the same. Your breakdown poses on the arms and torso will probably need to be different, depending on IK/FK, but the end result should be identical.
If you are getting some kind of "IK look," then my guess is that you are letting the computer do too much for you. Remember, the computer is the dumbest in-betweener on the planet, and it will ruin you every chance it gets! You have to use the computer's in-betweening abilities wisely, and that basically means not letting it go more than a few frames (max) without having a key on SOME part of your character.
Remember, YOU control the arcs that your character's wrists take. YOU control the way that arm moves and looks! Don't let the computer trick you into feeling lazy. It likes to whisper in your ear and say, "Hey buddy... you don't really want to save all those keys do you? Why don't you let me handle it for you? It'll be awesome, and you'll finish quicker! Trust me!"
Don't trust him! He's a liar!!! He's trying to fool you! Just tell him to mind his own business, and make sure you've put the appropriate breakdowns in place to create the arcs and paths of action you are expecting.