I don't know how to answer you on this. It didn't seem to be a problem in stream formation take offs so I guess it is a tried and tested method. In the case of the Vulcan the wing loading is quite low so any wing tip vortices will be small. The exhaust plume disipates with gravity and cross winds. Also the controllability of military aircraft is of a different order to commercial aircraft so issues like turbulence are probably better dealt with. I was once tipped upside down at about 50 feet in a Vampire T11 because we got too close to the aircraft in front on approach - my instructor was flying and we were number nine in a nine ship formation. Much opposite rudder and control column and gentle movement of the throttle to full power got us in erect flight and an embarrassing overshoot.
Hope some of this helps.
ACW