i had some scholl wooden sandals about 5 years ago, i too did what house of bamboo did - i had a bruise on my instep, which then hurt when i walked because of the moulded wooden sole...
my real issue was that i couldn't keep them on my feet though. my feet aren't very sweaty and being so dry they just slipped off. constantly. and i was always terrified of more instep-bruising, although thankfully that only happened once. i have been known to wet the bottom of my foot to keep them on.
then i got some birkenstocks and my whole life changed and i never wore them again. not what you asked, i know, but just my experience of wooden soled shoes.
but i never found wearing them jarring on the back, if that's all you're worried about
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