Well...my division's president (American) speaks Argentinian - Venezuelan Spanish (he grew up in those countries, expat parents), he seems to have no problem communicating with any given Spanish speaker. As long as they are understood, what is the problem not speaking a perfect Castilian Spanish?
No problem at all, but we have to recognise that Iberian grammar is richer and the tone while speaking is the same as writing. I wonder how Argentinean writers manage to place the accents over the right character... ienso: I have been working with people from Chile and very few use accents. If we do the same in Spain, would that be professional?