From the comments in Star's thread I am testing atm - loot seems to be better already
btw you don't need two exact avatars - TT gains of skill is what is important, and any other residual gains can be deconvoluted (like serendipity being a cross-profession skill)
As long as the avatars use the same (maxed) equipment for a month? it should null any anomalies - maybe ten manis each then measure their skill changes afterwards.
It should at least show whtehr it's a signigifcant/measurable gain or not (rather than 2%)