Hi mate.
I haven’t tried the fox but own a parachute and a switchblade.
I could wear the parachute all day even when it’s warm and will probs be wearing it all the time on my MTB in future following an accident with half shell on.
I find climbing with it no bother. I did ardmoors and the only time I took it off was when pushing/carrying bike from end of section 5.
I have only used the switchblade once and it felt pretty well vented as well but it was pretty cool outside .
I was in the same quandary but the fox was too much money for me but glad I got the Met.
I have a 58cm head and the medium just fits so if your head is any bigger I would opt for a large.