Thanks, John. The lens is 2.7kg, according to Roland's data. A bit better than the 500/4 AIP, at 3kg, and less than half the 600/4 AIS which does 5.65kg and I only use now if I can park the car at proximity.
Fully loaded though, with camera, hood, Arca Swiss plate, lanyard... I'm almost at 3.9kg, without the monopod. That I can carry for a day but I dream of the 600/5.6 PF