Can't say I have ever really tasted a well made Northern German Alt or even been successful at brewing a good one in the past either. These tend to be more like a smoother, clean fermented german brown ale, right? More or less?
Have brewed a ton of excellent Dusseldorf alts though. I enjoy them quite a bit.
Yeah, more or less, but browns tend toward a more prominent crystal/caramel/chocolate malt character, while alts tend to taste a bit more toasty. No. German Alt is a bit less bitter than Dusseldorf Alt.
Alaskan Amber was (was - N German Alt was subsumed into Altbier in the 2015 guidelines, so it no longer exists as a distinct style) one of the classic commercial examples in the 2008 guidelines. It's a very clean, quaffable beer. It's ubiquitous up here in the PACNW. About every gas station and 7-11 has it in stock.