I recently moved from a Nomad to a 6.6. The 6.6's suspension is more silky on the trail than the Nomads. The Nomad seemed to "thud" through the rocks where the 6.6 soaks them up in a far more refined manner.
As far as a move up to a Uzzi you are talking about a completely different type of bike, and the Socom is even further away from a trailbike. I have an Uzzi and love it, but it not a great trailbike. It pedals very well, but it is a tank and built for abuse. If you want a 'do it all' kind of bike I would say the 6.6 is a great choice. It will feel like an improved version of your Nomad. There is a 6.6 'slope style' bike coming from Intense that also may be of interest to you, it will be lower, slacker and tougher (than the current 6.6). But with all that said the Uzzi is an awesome bike as well, just not as fun to pedal up the hills on.