The earlier Duet remote software was flaky and would frequently lose synch with the server. I haven't had any problems with newer versions for some time.
I never get buffer delays, but my receiver is connected with cat5.
Sometimes wireless devices just don't get along. $100 for a different router isn't a big deal.
I have had to replace the Duet battery after a couple of years use. Since when do batteries need replacing? (sarcasm)
If you have difficulty navigating thousands of albums, perhaps start with 'artist' or 'genre' instead. The wheel is not the perfect interface, but short of having a device with an alpha keyboard, I think it works fine.
I will be getting a Touch soon.
I recommend anyone getting a Squeezebox anything, start with dbPoweramp and FLAC.