Not really. Maybe some will notice that weight difference, but with my average skills and riding style (trees) the traction is much more noticeable than weight.:) However there is more vibration when driving on trail.
I changed my series 7 to M770 and even in low snow, I can easily notice the difference. I did not make any other mods and my sled starts to wheelie so easily. M770 has a lot more traction and bites so much harder than Polaris tracks (no experience Series 9). Worth the money? YES