As a Redskins fan and a Native I never found it offensive. I feel most other Natives I have spoken with didn't find it offensive either, this is anecdotal. One thing that is not anecdotal is that this really never picked up steam until a bunch of non-natives thought they would tell me it holds the same value/context as the N word. This simply is not true and I have never been called a "Redskin" and never known any of my full-blooded relatives to be called that, not to say it didn't happen.
If the team was named or someone called me or my family Savages, Engines, or an Injun I would be offended as those are actual slurs I have heard.
This is my opinion and I am only speaking on my experiences. But I think this sucks because the Redskins have been a team favorite since I was born and I identified with the team because of that reason. If I am upset with anything it's that Dan Snyder is a F'ing A@@ hat and he should probably give some of his money to underprivileged reservations for monetizing on the Natives. But hell, I could even overlook that if he wasn't such an incompetent owner and put together a few winning teams now and then.