As for too hot - I don't know but I sure hope not. I just ordered a few skeins to have my Mom knit up some shorts. I have a nanny-made soaker from fishermans wool and my little guy never feels too warm in them.
If they do seem to heavy I'll have her add some and make them into longies!
I have 2, i lovethem. We live in arizona & it is hot here!! I have no issues since it is more breathable then PUl. I've had people ask & i tell them that i would rather my babies be in breathable wool then sposies!!!
Last week I made a pair of soaker shorts with Blue Faced Leicester and this week I am making a pair with Peace Fleece. The BFL is thicker/heavier than the PF but J has no complaints in wearing them, believe me it is hot here too. Maybe not Arizona hot but a lot hotter than it normally is this time of year.