I LOVED my Reefs and wore them for several years, but alas, I believe they caused my PTTD  (Posterior Tibial Tendon Dysfunction). I am a California Girl though - I need my flip flops!  I have never owned a pair of Vionics, but my MIL suggested them after I found out I had PTTD  and needed to wear sandals with adequate support. I ordered the suggested size 9s (I can wear anywhere between an 8 and half or 9, depending on the shoe). My foot fits great in the foot bed and the foot bed itself is AMAZINGLY comfy! The straps though, leave much to be desired. There is so much slack and room, that these rub way more than they should as I walk because of it. According to my MIL, her current pair similar to these do not do this. So I am not sure if it is because of the certain pattern, color or what (I bought the white with the brown accents). Next time I may have to try them on in a local specialty shoe store first...