You do need to make sure the net can't be pulled down. The net over the spare bed at Mum's fell on me 'cause it wasn't tied up right so I wouldn't want bubs to be under swathes of net if it did come down. Probably best to go to a baby shop & see what's available.

IMO a cotton net is better - I think the air circulates better, but I could be imagining it. They aren't as easily fond as nylon ones however.