I picked up both the 32 GB Wi-Drive and the 500 GB Seagate GoFlex Satellite a month ago. The Wi-Drive connects with both Kindle Fires, but the Wi-Drive app is not compatible with the Samsung Galaxy Tab 7 Plus. The GoFlex Satellite connects with all three, although the GoFlex Media app had to be sideloaded onto the Fires. We like being able to use the bridge mode of the Wi-Drive so the Fires can stream movies and still have wifi access. That's the one drawback of the GoFlex Satellite, connect to it and you have no wifi. The GoFlex Satellite has much better storage capacity, 500 GB v. 32 GB, but having the wifi connection gives the Wi-Drive a little edge.
The Wi-Drive is now $80 at Amazon.