I had the Salto for 2 years and loved it. I got the M3 in April. I've paddled it in Cali, Durango, CB and it is sweet. It handles much better than the salto. Turns better, resurfaces better (goes a little deeper however) outfitting is better, The cockpit has as much leg clearance. The M3 has many great safety features (center pilar, bomber pin grabs). The M3 is much lighter and easier to carry. Definitely needs a nose cap (which they do not make yet) The plastic is much softer and will not last as long as a Salto. All and all they are both great boats. I think you need to decide which pros are more important to you.
Happiness is a way of travel not a destination