MongoDB was initially designed to beat other nosql systems in benchmarks, is what I take away from reading about it. Someone took issue with that and wrote an article. "MongoDB lies" and "is slow" were some of the claims made from your link #1.

Now that these issues are gone, by having reasonable default settings for write concern and journaling, how well does MongoDB do in the benchmarks today?

Rewgarding default settings, how is "w=1" considered a safe write? The data exists in a single node and has not been propagated. If you only have one node then I guess it's as safe as can be. Is MongoDB suitable as a single node installation though? I would have thought "w=2" or "w=majority" would be the "safe" setting.