Most Phalaenopsis should grow fine this way as long as you water appropriately. They're easy enough to grow mounted on cork, which provides pretty similar conditions. Is there a particular reason you don't want to use medium? I've had good success with Phals in baskets with sphagnum, coconut fiber, LECA, and various combinations of those.
In my (limited) experience many Phals are actually pretty xeric-tolerant, though they generally grow faster and bigger kept moist than if kept dry. It shouldn't be too hard to grow Phals well in empty baskets in a greenhouse setting, but it would certainly take more watering than if they were in any kind of medium. Danny, if you're worried about medium breakdown and repotting, LECA or lava rock will make for happy roots and should outlast the basket they're in...
I have seen phals mounted...I also have seen it in a vanda basket; but it has to have moss in the basket...it cant be bare root even if the basket is made out of wood. Please look up the phalaenopsis culture and you will find out why media is important.