I've had 50 chicks on wire(1/2 inch) since the end of week two. Had them on paper towels for 3 days, then pine shavings for 11. The main reason I used wire is because I built a large brooder for them. Shavings wouldn't have been practical for what I was doing. Also, 50 chicks make ALOT of manure. Shavings are dusty, smelly & expensive.
The wire works great. They haven't had any foot problems. Their feet are getting huge by now--they can run at full speed from one end of the brooder to the other. They're still able to peck at the edges and support boards... they still peck in their food dish. They're not able to scratch too much, but they will in a couple weeks. It's not going to hurt them to go w/o scratching for a little while.
I chose not to use 1/4 wire... I didn't think it would be wide enough for the poo to fall through and would cake on the wire(sorry that I used the words, "poo" and "cake" in the same sentence). I have a large tarp under my brooder. Poo falls through wire, onto tarp, and dries(reducing odor). Can be changed out when needed or simply can be thrown away at the end of the brooding period.
Until some horrid event happens to convince me that wire is evil or inhumane, I'll never do it another way.