Uhm, grids or wire floors usually aren't a problem for rabbit feet, with the excemptions of rex furred and giant rabbits. If it's only the litter box I wouldn't expect problems even with those breeds.
That said, my rabbits have their litterbox right under the hay rack, no idea how I could get them to pee anywhere else, where there's nothing to munch on. A grid would be instantly covered, being rendered pointless.
I'm happy with wood stove pellets under a layer of hay, I can roll up and replace the layer of wasted hay a few times before I have to change the pellets (I just scoop out the worst spots when replacing the hay). I can't imagine a grid being as efficient in odor control.
I can't imagine those grid working well, but I haven't tried it, and I can't remember of reading about positve experiences. It might depend on the individual rabbits, but mine would just pee and poop wherever the hay rack is. ( I know, was away for 5 days and as a backup to the teen feeding my rabbits I left a big basket full with hay on its side in a different room - they instantly made this backup feeder their preferred peeing spot. Didn't think to put a litterbox there too, what a mess)