i've been meaning to post this sooner, but i've been out of town and just haven't got around to it - but pleased to report:
while we were out of town, the female has taken up the GBTA very nicely!
i was still kinda worried, because in the mornings and late evenings we always would see the GBTA hiding in the back under a crevice, where there is not much light. but this weekend, in the mid-afternoons to our surprise, the GBTA would come out and expand very nicely into the light (as in the picture!). so now i am wondering whether it's been doing this every day - wander along the rock into the light for a few hours a day, and then hide back under the crevice at night (it seems to like this crevice that's kinda hidden). is this type of traveling behavior normal? in any case, it's a joy to see the female perc and the GBTA together. the male however, has not been accepted by the female yet (they are courting i think), and at night he floats nearby the anemone since the female won't let him in 
while we were out of town, the female has taken up the GBTA very nicely!