Naw, it's still an iron alloy funny enough.
What did you think it was polymers?
Just kidding. Not that it was funny but it my type of humor (the not funny kind).
I'd give the edge in terms of power to Magneto, but Iron Man's no stranger to magnetics. Since Mags can't directly affect the armor he would have to;
1. Overwhelm it with energy (not easily accomplished),
2. throw something big at it (considering Count Nefaria has hit Iron Man with a cargo freighter and he survived, Iron Man should be able to weather anything Mags can use as a projectile),
3. disable the armor with an EMP (thankfully it seems Iron Man has finally figured out to shield his power source from the effects of an EM pulse).
Now can Iron Man penetrate Mags defenses?
Probably given time he should be able to find a way around them (sonics maybe?) or bash through them in time.
I'd give Iron Man the win 6 times out of 10 against Magneto. More if he has time to break out a Magnetobuster model.