as long as the items can all be obtained in game through simply playing the game its not a problem imo
uncharted 3 multiplayer as you mentioned had micro transactions, for example, however, all of the special guns and hats and so on could still be obtained by simply picking up treasure drops which is how i got them
so it pretty much did not impact upon me at all... i suppose competition may be steeper because your opponenets can get gear more easily but if you are a skillful player it shouldn't really matter much imo