Expensive and not at all adaptable to the gunship role....but what the heck....it was sold as being "all things for everybody" wasn't it?
Compare the size and shape of the Osprey to say....the Apache or Super Cobra...the agility....and one begins to think it might just not be the best choice for running and gunning as done by true Gunships.
If you try the AC-130 concept....then a Chinook or 53 makes a better choice.
The US Army tried the Armed Chinook back in the mid-60's and gave it up as a bad deal. Huey's were cheaper.