If you mean control function in conjunction with XP8, yes!
no issues found with the combination T4/XP8.

@Cams
yep - wow, waiting so long to give this answer like sj :-)
stikx

One thing to think about is if your wireless router/access point goes down your RTI handheld won't work.  We had this happen with our office T4.  Wireless network would randomly "disappear" and we would completely lose functionality until we rebooted the WAP.  

It was a faulty WAP, but just something to consider...

Given the option I would have done a Zigbee T4, but when it's working it works exactly the same on Wifi.