Riff Raff: I hear what you're saying and there's no denying that with those massive pylon-wings you should be able to lift some impressive loads - especially if they develop the rolling take-off technique.
But the 'planform' of this contraption is considerably larger (and therefore in my view more vulnerable) than the Raider concept. Plus, with the tilt-rotor you have two unique heat signatures effectively giving your assailant unnecessary opportunity.
I understand the advantages of swift troop insertion/extraction but .. at what cost? Financial analysts predict that US defence budgeting will come under increasing strain over the next two decades with the role of the Defence Secretary requiring skills more closely associated with that of alchemy than tactical politics and at the moment I simply can't see how titlt-rotor technology can be cost-effective. I may be wrong.
TukTuk: As Phlying has said, the larger troop-carrying versions are designed to be self-deployable .. if not through in-flight refueling then by leap-frogging (if the US has sufficient allies in the right places at the right time to accommodate their fuel stores).
Re: Door gunners .. surely these are a thing of the past .. except for movie-makers! This function can be far better served by a weapons officer or second pilot using fore and aft mounted turrets through electronic sights. If it doesn't already exist then I am sure it is only a matter of time until this function is completely automated with the role of the weapons officer/second pilot merely being that of confirming that the computer has identified a hostile as opposed to friendly target.