These clogs are extremely comfy right out of the box!  I have the FitFlop sandals and love them also.  I wear a size 8 in FitFlop sandals, but a 9 in the clogs (I'm normally an 8-1/2 in other shoes).  I also bought the cougar color clogs because I love these so much.  I have fallen arches, bunions, plantar fasciitis, neuroma, etc. - so finding comfortable shoes is difficult for me.  I highly recommend these.