I bought the H4n just 1 week ago, thinking of using it's XLR and internal MS matrix (i got a MS setup based around 2AKG blueline), i did record already lots of stuff (mainly ambient exterior) with the 2 onboard mics and they seem very similar to the sony D50, very detailed, i haven't get around to do a live 4 channel recording with the all system, I've tested it (stereo onboard) with live acoustic music, a jazz trio, piano, sax and double-bass, and the stereo mics are very good, better than I ever thought, with detail and a wonderful wide stereo image... (I was deciding between sony D50 and tascam DR-100). Perhaps I get a chance next week, I'll post something...
Otherwise I'm very pleased with it, quite and detailed, even with XLR/48v input, one of the best all around recorders, and the price... beats anything...