El Capitan...I'm still using continuity w/Yosemite & iOS 9.0.2, with a BT4.0 dongle and using the continuity activation tool.
There is an update to the continuity activation tool for El Capitan as El Capitan has more locked down kexts (things have been changed to increase OS security), however, it only works with BT4 boards, not working with dongles, so, I'm waiting to update to El Capitan, but, if you have a BTLE board in your Mac, it might work.
Lost my handoff as well. I upgraded my bluetooth card on my early 2011 MBP and was working with Yosemite and also was working on my MAC mini. If you check your system report handoff is now "not supported".
What's happening to me is that the phone call rings like normal on my laptop but when I go to answer the call gets dropped. Also when I try to make a calls, calls don't go through.
I am using El Capitan 10.11.2 beta 1 and Safari handoff does works for me.
I don't check other features, though.
MacBook Air early 2014 + iPhone 6+ loaded with iOS 9.2 beta 1.