There's sound and there's usability.
The iPod Hi-Fi / Sounddock can be beaten in terms of quality, and far bested for sonic imaging (since you can place the speakers apart) by a powered monitor costing £150. However after you've added a charger, universal dock and remote that's up to £220.
At this level, you won't be hanging in front of the speakers listening to every nuance so I say consider your use carefully. The 'separates' option may sound better especially to the audionerd but the Hi-Fi is more casually usable. It is however in my opinion fugly, but I use it more often than the powered monitor / dock. Don't quite know why. I just like using it better.