Thanks for replying Imran. I'm definitely going to wait to see how I like the second placement, but I was worried about how companies generally deal with < 100% success with deliverables.
On the other hand, if you wait until the last day before announcing that you're only 60% done, that is your responsibility. Don't be that guy. You should be talking to your manager now about how far along you are and what is an achievable state to leave the project in for somebody else to pick up (actually you should have started this some time back if you haven't already). e.g. you mentioned a lot of work went into gathering requirements - if you are not going to finish the project then that work probably needs to be captured.
Communication is the key, and that's got nothing to do with whether you're doing coding or marketing. Nobody is going to make any inferences about your marketing abilities from your coding abilities or vice-versa, but if you prove yourself incapable of communicating with your team in either placement then, well, that would be the time to start getting worried.
Failure is not always bad, but trying to cover up failure always leads to very, very bad things and it never, ever works. Remember that and you'll be fine.