Brokenhearted!!!!  I love Orthaheel/Vionic shoes and I own MANY pairs.  I ordered #331 Heritage with full confidence but was completely disappointed.  The back of the heel slipped up and down - no way I could wear these.  They were NOT true to size because I always order the same size and have never had a problem with fit.  I hope this is not a harbinger of things to come and that quality control is slipping!  I have come to depend on this brand of shoe and the prospect of trying to find another brand is daunting.  Now I have to go to all the trouble of sending them back.  I had planned to order another pair in the same color but that is obviously not going to happen.  Orthaheel/Vionic you have really let me down!!!!