SAS, thanks for the article. Some food for thought there.
In re crashes due to roll off or other turb/vortex related mishaps ...
Over a decade ago, a Navy T-34C crashed after joining up on an F-14 to perform a visual gear check. If I remember the details right, the F-14 crew had asked tower for someone to give them a visual since their gear was down, or so they thought, but their gear indicator wasn't indicating "safe."
A T-34 was nearby and obliged.
Sadly, the unsafe gear pattern wasn't high enough, in this instance, for the T-34 to recover from the tumbling and buffetting (unexpected) that was induced by a turbulence/vortex originating from the F-14.
The caution about "stay away from 5-7 position" is interesting in re the Osprey formation technique. I suspect that if the T-34 had joined up from abeam, or the 8/4 position, that mishap might never have occurred. (My memory is a bit fuzzy, if anyone knows more about that mishap in detail, please correct what I may have gotten wrong.)
There are some rules of thumb that are taught to every pilot regarding wing tip vortices in the landing environment, typically summarized as "make sure you land beyond the touchdown point of a heavy that you are following" which accounts for the settling rate of wingtip vortices.
It appears that for Osprey, another layer of awareness is added to the wing tip vortex caution, given its method of lift creation in the flight modes that are in more "helicopter" than "fixed wing" configuration.