I know everyone's experience is different but I went from a Multitec to a System 6 and then back to a Multitec!
Found the System 6 noisier, not as comfortable and a lot of wind around the back of the neck, but the thing that really killed it for me was the front vent on the System 6. Despite being told that there was nothing wrong with it I found I would get a really cold patch on my forehead (it was January when I bought it). I could only wear it for 20 or so miles before the cold became unbearable (at that time of year). BMW refunded me and it was straight down to my Shoei delaer!
Sorry - no experience of the Nolan.