There is Bluetooth software and there is Bluetooth hardware. The upgrade from OSXWifi gives you Bluetooth hardware 4.0. As mentioned I have one of these upgrades and it gives me Bluetooth 4.0 hardware which fully supports Apple's Continuity and means it also supports Bluetooth LE (low energy).
See this article. http://www.idownloadblog.com/2015/10/16/how-to-find-your-macs-bluetooth-version/
With the OSXWifi upgrade it lists a LMP value of 0x6 therefore Bluetooth 4.0 hardware.
I don't have access to the very, very latest Macs but I did check the latest Mac mini which is now an over a year old design and it also has Bluetooth 4.0 i.e. 0x6. Therefore I am not convinced any Mac has Bluetooth 4.1 as yet. In fact this article which lists the Bluetooth model supposedly in every model of Mac confirms this. See http://www.everymac.com/systems/by_capability/macs-with-bluetooth-different-blue tooth-capabilities.html
With regards to the OSXWifi upgrade, the original Bluetooth and Wifi in a classic Mac Pro is two separate cards. The upgrade replaces it with a single board which does both. Remember this is the genuine Apple card from a newer Mac. The upgrade consists of an adapter card to allow the newer card to fit, the newer combined Wifi and Bluetooth card, and also a couple of cables.