Not super flexible, but much more comfortable than HFS II
"Fit is generally good, although the toe box is unexpectedly tight without removing the optional insoles. Weight and balance is good, with an overall good sensation of the ground through the sole, but it's not as flexible as I'd like, having grown used to the original HFS shoes. Worlds better than the HFS II though, which is super uncomfortable IMO. I wish they'd bring back the old one! Not tested these in adverse weather yet, but they look to be a little more weather-proof than the HFS shoes. First impression is very good, but not amazing."