The iAutomate system provides signal strength between tag and receiver so you can speculate if a tag is near or far from the reader (I use this to determine if the trash is at the curb or beside the house on trash day). The iAutomate system can also report movement using the motion sensing tags and some of the tags also have a tamper feature that indicates if they have been removed from an object.
I use the motion to trigger some reminders the first time my tag is moved each day. The tag's in my wallet, so this is usually right as I'm getting ready to leave the house. The motion tag also acts like a theft deterent for my SUV that is parked in the driveway... at night if movement is detected (only takes a slight movement), the garage, yard and driveway lights turn on. Seems to work well, but on the occasional night that we'll have wind, even this is enough to trigger it.
The other advantage is the ability to adjust tag "timeouts" which is the amount of time before the system thinks the tag is gone. The tags also transmit every .7secs so updates happen quite quickly... not sure what the transmit rate of the less expensive gear is?
It seems that range might also be different between the systems... I see tags being received on the cars about 2-3 houses away which is at least 200ft. The readers can be configured for long and short range to provide different coverage which can be tailored for different applications where I think the less expensive gear has a couple different transmitters (one long range, one short range).
RFID is neat stuff and lends itself well to Home Automation... with the announcement of the iAutomate MIRACLE interface and this new RFID gear sounds like it has a bright future!