As with any question on usage you need to track your own usage to answer that question. Two different people could have the usage you describe and have very different actual data usage.I travel more or work but mostly will use it for web, email, local music, etc. one thing I plan on using a few times a week is the navigation feature in ios6. Would 2gb be enough, will 4gb even be enough?
The "LTE uses more data" meme that's being parroted is nonsense. Usage varies by person. LTE's faster but it doesn't automatically use more data.Just wait until people start finding out how much data they use with LTE on the next iphone.