Whatever queue there is suspect it's got to be better than the landside transfer experience. To try and safeguard our luggage last week on a MAN-LHR-JFK flight we chose this option - 40mins from bags disappearing into the abyss from the plane (50ft from us) to arriving on the carousel then another 1hr 10mins to get down to the platform, get on a train, change trains then arrive in T4. After the rigmarole of all that T4 bag drop and security was a breeze !