I know conventional wisdom recommends not harvesting yeast from worts > 1.060 due stress, but I assume this also means that you harvested after they have stressed themselves fermenting to terminal gravity.
I have a 1.072 wort that I pitched Saturday evening with ~85 ml of top-cropped WY1318, harvested last week. By Sunday morning things were well on their way. Assuming the ferment has not reached terminal gravity by tonight, does anybody forsee any issues with taking a crop of this yeast for future use? I would only harvest ~ 1/3 or so of the cake to ensure that there is enough left to get the job done. FWIW, at this point I can see that the "dirty" layer/braunhefe has already been pushed to the sides of the fermenter.
The assumption here is that the ferment isn't completely finished so the yeast shouldn't be too stressed yet.