I?ve periodically posted about my success stacking 511s with two different drivers to create a pseudo- large format driven multi-cell except with a superior HF and a ?tighter? pattern control [especially vertically] to a lower frequency, so see no reason why stacking 811s with the 902 running ?full? and the other rolled off up high won?t work.
FWIW, Cal has been pleased with his stacked 511_811 combo.
All that said, if you will be sitting fairly close, then the extra pattern control might narrow up the 'sweet spot' too much.
Bookmarks