I have the HD5, love it, although it has developed the crack between the directional buttons that people are talking about. I am quite concerned about that issue because crack developed with only about 12 hours of extremely gentle use. Since others are also experiencing this issue, I am wondering if this will be a major problem eventually.
As far as your concern about Sonicstage software. Personally, I wouldn't use Sonicstage as a reason not to buy. I've been using for a while because I also own a Sony MD player. I think the software is easy to use. The only problem I consistently experience regards the connect music store. Every couple of weeks I can no longer view my account or use the service and have to go in and clear my cookies, internet files, and reset explorer. That is a bit of a pain since then all the other websites I visit no longer recognize me. But as a music management tool, I have no complaints - once your music is loaded into Sonicstage, transferring to the HD5 is very quick and easy.