Flex tree

Heard from some people it's really great, however was told in one store people complain about flex tree. Does anyone have one? What do you think then?

My trainer said they can be bad for arch support but.... I don;t know for sure!! :)

Thanks, D! I heard so much different that's it's rather confusing. However I read (and do agree) that good solid tree is better than flex. The only problem how to find out it's good. Lol!