The D-link creature does not appear to support FLAC, though perhaps as with the Roku, you could use Slimserver to broadcast to it too.
Happy with my SB3, not interested in video broadcasting, so it is not for me - I did some research before buying the SB3, and encountered both these options.
Both have their applications, but for me, the SB3 is the way to go... pretty much cost neutral, is it not? Maybe moreso up here in Canada.