Difference between the dock options

[jonnnny]

So from what I've read, there are three dock options for the current thinkpads....

Mini-Dock
Port replicator II
Dock II

Is the only difference between the mini-dock and the Port Replicator II the 4 instead of 1 usb slots?? I read the mini-dock has its own power supply... but how is that different from buying another ac adapter for the port replicator II?

Is getting a mini-dock really worth the extra price?

Thanks thinkpads.com