On the 340, in my previous company, we used to transfer outer fuel manually after landing at our European and North American destinations, never had any unusual icing problems, did not tanker to the Caribbean. Flew the NG cannot remember any issues outside the ordinary. On the MD we almost lost an aircraft due to ice-nine on takeoff roll and double engine failure prior to V1, after which the policy was for engineering to transfer as much wing fuel to the centre tank after landing then top up the wing tanks using warmer fuel from the station, that seemed to work ok. At my present company occasionally find ice under the wings after ULR flights even though the OAT is 46 deg C (how do you ask to de-ice when its too hot to walk about
), normally is gone by the time fueling is completed.