Or the Sunrace small cassette hub that allows 9t cogs, I hear it's a Capreo clone. It comes standard with the current R&M Birdy 10-speed. But I wouldn't recommend that, as it's too weak: Birdy thread

With the SRAM 10-42 cassette I imagine one would have trouble with chain rub on the large cog. I had trouble already with 9-36 and 52 front, had to space the chainring out to a pretty bad chainline to avoid rub. (One more reason why I went for an Alfine instead.)