Seems really strange, huh? Well i said braking is poor, but i'm used to excellent alloy rims or pretty powerfull Shimano deore disc brakes on my mtb so a lot is "pretty bad" in my opinion.
i don't think that the weight has such a impact since, as i said, the stiffness really makes up for it.
I mainly love them since im more of a aero-geek, so weight and cornering ability isn't all that importnat. Braking needs to be sufficient and not more. For mountians i use disc brakes or alloy rims
and it all sounds quite a bit exaggerated