There would not be any heat buildup from the unit like there is with a refrigerant type a/c unit, so that isn't an issue. The biggest problems would be water management and getting enough airflow. The things suck huge amounts of air - you'd need the combined surface area of the four sides with the pads on them with no restrictions (and probably more to account for any duct losses), and that's huge. There's good reason why they are on the roof.
Also, while they can work great in low humidity, keep in mind that as the humidity rises, they work less and less which may be when you really want it (on those hot humid rare days). Just like you sweating, it doesn't evaporate on a humid day, or if it does, not fast enough to keep you cool. Your furniture may not like the big swings of humidity between seasons, but your mucous membranes may appreciate the higher humidity levels. Because of the huge amounts of air moved through the unit, it will suck in large amounts of pollen and dust. The pads will need to be cleaned and or replaced periodically, and the thing flushed out (part of the water management issue). Also, you have to leave at least a few windows open in the house, or there'll be no air movement and no cooling. If someone is home during the day, this may not be an issue.