Mandatory reserves in Qf are the same for both aircraft. I hadnt thought about the seats and that is correct it would lower the usefull load if the 400 was refitted. Just a snippet of info, i paxed Lax/Syd in Feburary on duty travel and my bag was put on standby. When queried the checkin person remarked that at that time all staff bags went in a seperate container and were only uplifted if there was weight available after the fuel uplift. Dont know if thatts still the case. From my observations the 380 carries vertually no freight ex LAX with full paxs however the 400 gets about 4/5 tonnes with full paxs.