A media report which I read recently said that the weight savings which had been achieved with the recent interior refit, etc. are almost equal to the extra weight for the mods, etc. Hence no significant change in the range/payload situation.
With the a/c being out of service as long as it has been and the ramifications of the mods surely any responsible operator would want to do some proving flights with non fare paying passenger?
I say all power to BA's elbow to get this beautiful bird back in the sky again and if some of the staff who have worked hard to get it airborne get a freebie then they deserve it!