The most compelling reason to go with the ThinkPad Dock II would be to get the Ultrabay 2000 device bay and the half-height PCI slot. If you dont need either, then the Port Replicator II or Mini-Dock ...
Dell's specs don't list an E-SATA port for the E-Series port replicators, but zooming into the pictures on the Dell site show what looks to be a combo E-Sata/USB port on the back (giving a total of 3 ...