I see little reason for an iPod dock in a stationary system.
Its all down to aesthetics and ergonomics's. The iPod dock would charge my iPod, on paper looks great and needs no further power supply or cable runs. Ergonomically, for me, if I can read the display at a distance, its the best solution.
I have had Squeezebox for many years and every time a new software release comes out, I get worried. It once needed a minimal spec system (I run it on a P3/500 w/512MB), but now its well below the published minimum specs (not that I can find them) and seems to be more sluggish with every release - one day its going to break and suddenly a 'cheap' solution is going to require a different PC and the time and cost implications of that. I am worried that this may be the case if I added a Duet.
The Sonos looks great, but I can no longer justify the money. Plus it would need a couple of long trailing wires. If I was starting again, I would almost definitely go Sonos, but I have Squeezebox and F80 and I'm not a throw away kind of guy. And the wife uses the clock display on the Squeezebox almost contstantly, so no chance of slipping something new in without being noticed.