Obviously you can wait for first hand experience from keri, but I think the traditional Moby fabric (stretch cotton, not sure if they've made any recent updates) would be WAY too hot for Houston. (I'm from Austin and living in NM now). I used my Moby a lot when it was cold here and barely put more than a hat and a sleeper on my August born babe.
I wonder if you could make a Moby out of some solarveil or something else really really light? I mean it's basically just a few yards of fabric. It seemed like our Hotsling was pretty hot too in the beginning because they snuggle in so much. A lightweight mei tei might be good?
DD2 got new CD's and I'm drawing a blank as to anything else. They're so close in age hardly anything she needed had even been packed away.