This is what the rimless guys are using. The latter part of the thread recommends using the black, UV-rated mesh netting that has 1/4" holes. BradleyJ uses this and actually doubles up on the layers.
However, it's still a risk with gobies and fairy/flasher wrasses as there are some people who still have them jump through this netting. But, it's the best out there, if you still want to maintain the open top look.
http://www.reefcentral.com/forums/showthread.php?threadid=817485&perpage=&pagenumber=1
Egg-crates will protect your fish if you have bigger fish. But, wrasses and gobies will definitely jump through it. You also get a significant amount of PAR decrease with the egg-crates, or so I hear.
A number of reefers have reported that the mesh doesn't impact PAR.
Hope this helps.