That depends on the head, but I wouldn't expect much change. But as said above, if you turn a conventional spray pattern upside down, you will end up with lots of water right under the head. The spray pattern needs to push the water up and out, to get an even distribution.
Here's a problem though. If you put the piping way high, many spray patterns may end up hitting your roof or walls. Why not run the piping just above the height of the shrubs on the tables. That way you don't need pop ups or risers on each head, but the heads height is placed for the optimal spread.
Or you could go with misters from up high.