Continuity/Handoff depends upon having the latest WiFi/BT chipset(s). The Apple Support Document, which P1LGRIM sited, reflects the Apple Macs and iDevices with the appropriate WiFi/BT chipset to support Continuity/Handoff.
If you buy the iMac WiFi/BT card in the OP, you'll have Continuity/Handoff. I'm running the iMac WiFi/BT card in Hector with a System Definition of MacPro3,1 > see my
post here for more information including a screen snapshot of the System Profile, Bluetooth information.
I've also upgraded my real Mac Pro (2008, 3,1) with this card and adapter from
http://www.osxwifi.com/apple-broadc...th-4-0-with-adapter-for-macpro-2008-2007-2006 and will be upgrding my 2010 Mac Pro (5,1) shortly. So, Continuity/Handoff works with the iMac card.
Disclaimer. I have not used Continuity/Handoff between Hector and my iDevices. But, tonymacx86 and several other moderators have done so and report success.