I can't comment on the Houdini, but the Wraith has pretty decent breathability. In +70F weather I barely sweat all weekend with it on. In direct sun though with a L/S I had to take it off. It does let in a small amount of air in a wind so should be pretty good.
My only gripe with the Wraith is that it's DWR doesn't stand up to AZ's fat rain drops. In most misty-drizzle rains like the rest of the world it's probably fine, but if you have really heavy rain drops in your area it will wet out surprisingly quickly. I may revivex mine to see if that helps the problem.
As for sizing, they are pretty snug with little stretch. I'm usually a 36-38" chest depending on climbing activity and in the small if I fully bring my arms across my body the back is tight and limits the extremes of arm mobility. Not really noticeable while hiking, but occasionally happens while climbing.
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