yeah, half kilo is what I calc'd a while back aswell.
on a weight weenie build I can see it being a dealbreaker but not if it's a mainstream weight (25-30lbs) bike.
as for weight balance, a guy I met riding a Rolloff'd nicholai made a good point that we've added a kilo to the front of our bikes with shock forks so adding 5-700gr to the back shouldn't make a difference. I expect it'll take some small amount of getting used to but not much.
I have one on my commuter and they are great. Not sure about offroad tbh as they dont really shift under load at all well (although this would actually be good practice as your deuralliers shift so much better if you avoid loading them during the shift). It's also a bit of an all eggs in one basket solution where if you have a problem with a 3×9 setup you can jury rig a solution to get you home, not so obvious on a gearbox but then I covered 5,000 km on mine last year and didn't have to do anything except tighten the gear cable.
I like the look of the 11sp, it's almost 2×9 gear coverage now iirc which makes it a much more useful spread than the 8 (although my 8 is a fine spread for commuting and touring without changing sprokets)
