One other thing does come to mind. When it is hot in the summertime (115F+ here) a mesh seat lets some of the perspiration evaporate from your back. You might just end up swimming in your hard shell seat. I've read that complaint from some riders who post on bentrider.

One of the techniques I use to ride in ugGodly hot weather is to get wet first and then ride. It takes about 4 miles at 115 degrees and 10% humidity to go from soaking wet to bone dry. That includes my back so the mesh seat must allow quite a bit of air movement.