Thanks for the responses everyone. Ill probably end up getting a cab that is 1200w or so. Right now my rackmount ampeg is only 450w, what would be a good power amp to pair with that? Or would it be better to get one powerful head? Thanks
IME power "ratings" on cabs mean almost nothing. efficiency/sensitivity/tuning/speaker surface area mean alot more than wattage. a 450 watt head through any decent 810 will be crazy loud. just dont run the amp to "clip"

.. it was a great cab but soooo heavy. never buying an 8x10 again unless i have roadies