I would have thought that Wifi location would win hands down for zone. Problem with most RFID system is that they are new technology, with Wifi your dealing with existing technology and thus have a better idea on their integration and if they will interfere with equipment.
The thing is it's reported that the number of free IP addresses will soon be depleted and the move to IPV6 is thus more urgent. Even if someone doesn't have more than 17891328 assets (including PC's and printers), if most systems migrate to IPV6 can current devices easily be converted to ipv6?
