I have the SR7005, but no experience with the other units you mention.
My impressions of the SR7005 networking capabilities are generally very positive. All my music is on a Windows Home Server coded as FLAC and run off a Twonky server. It is100 % reliable and the performance is excellent. The only issue I have is that it doesn't play files gapless - why is this such a big deal to implement?
Anyhow, with respect to the online music - LastFM is very reliable and I use it all the time and quality is ok. Napster is not so reliable - given how reliable LastFM I think it is the service rather than the SR7005 that is at fault.
Hopefully Spotify and the high bit rate version will eventually come to the SR7005.