Following the guide of Insignia NS-PCY5BMA Bluetooth 4.0, Macintosh Yosemite 10.10.2, and Handoff, Handoff is still working well, even on Apple’s current 10.10.4. One issue that will creep up, is that every time the system is updated, the Bluetooth kext is replaced/updated. Luckily, only 2 things need to happen to restore functionality.
1) Re-Patch the plist in /System/Library/Extensions/IOBluetoothFamily.kext using the same procedure and code as before.
2) Re-Run the Continuity Activation Tool to enable Handoff for bluetooth dongles.
Once you do those 2 items, a quick reboot should prove to re-enable Handoff as before. If not, just verify that the system sees the Bluetooth dongle and then run CAT (Continuity Activation Tool) again to verify everything is patched properly.