Feelings toward/experience with the Canadian Nuna Pipa car seat?
Nuna Pipa Car Seat | BabyCenter
Car seat - Nuna Pipa | BabyCenter
Infant seat: Expensive vs Inexpensive?
I lived in the southwest for ten years and totally hear you on the heat and not wanting to cool the car down every time.
My friend always had an insulated water bottle with cold water in it during the summer. She would sprinkle the water on the metal and plastic parts and then pop her daughter in the car seat. This took the edge off quite a bit and it was so dry that the moisture was zapped up pretty fast.
As for which seat to choose, keep in mind that even the cheapest seats in the US have to pass the same safety laws as the expensive ones. So spending less doesn't mean getting less safety.
I have the Chicco Keyfit 30 and loved it - my LO has almost grown out of it and we've moved onto the NextFit by Chicco.
ETA: You've already got the safety bit figured out! Sorry - I couldn't see your post while typing my response.
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