Handoff with 2011 Mac using El Capitan
2011 MacBook Pros can support Handoff/Continuity 
  
After doing some research for the past few hours there might still be chance for the 2011 macbook pros to get the features that require bluetooth 4.0 / LE

As it turns out the 2011 MacBook Pro can use the same Airport/Bluetooth card as the mid 2012 Macbook pro and its user replaceable so by replacing the 2011 macbook pro Airport/Bluetooth card you should have the ability to use Handoff/continuity

After replacing your bluetooth card with a Bluetooth LE/4 card: Make sure the Bluetooth card is BCM94331PCIEBT4CAX (if it doesn't have the C then its a Bluetooth 2 card which wouldn't work) 

And away we go!


on your desktop press command+shift+g
type: /system/library/extensions/
find: IO80211Family.kext in the extensions folder and copy it to your desktop
on the new copy, do show package contents > Contents > PlugIns > AirPortBrcm4360.kext > show package contents > Contents > MacOS > open AirPortBrcm4360 with HexFiend
Text search Mac- it should be followed by a number 
type the below code in terminal this will show your board id example early 2011 macbook pro is Mac-94245B3640C91C81

ioreg -l | grep "board-id" | awk -F\" '{print $4}' -&gt;  94245B3640C91C81 for mine

replace the first number in your kext with the number u get in terminal 
save it 
Restart your Mac and hold Cmd-R to boot in recovery mode
Once rebooted, open terminal and type in the following code: csrutil disable
Restart your Mac in normal mode
go to terminal and paste:

sudo nvram boot-args="kext-dev-mode=1"

delete the original IO80211Family.kext in system>library>extensions
restart 
your wifi will not be working after restart
use kextdrop to install the modified kext
restart 
your wifi should start working again after installing the kext and restarting
Restart your Mac in recovery mode again (holding Cmd-R when you reboot)
Open terminal and type: csrutil enable
Restart your Mac
go to system preferences > general and there should be an option to enable handoff


These are the exact steps I performed with OS X El Capitan on a 13 inch early 2011 macbook pro and got handoff working with my iPhone 6 running iOS 9.1

Good luck!