I have used both the NP Mirage and Flash last month while kiting in Cuba. The major design feature is the Forged Aluminium bar. Both models are very light. The back support is very good in both models with IMO a little better in the Mirage model. The Mirage is cut lower on the sides which is very noticeable when riding. Once again ,with a kite specific hook, the bar is star of the show. The sizing is on the large size. If you have a 34" inch waist,you could easily fit both and L or M. Try one on if you can.
Great Harness!, give one a serious look!