I use the engage 65 stereo every day and am thrilled with the sound quality.
I chose the engage 65 because the engage 75 didn't do so well in a test regarding sound, but I didn't test it myself. In addition, DECT was a must for me as a radio protocol (much better range), because Bluetooth and WLan share the same frequencies, it can lead to problems (but doesn't have to).

I have not tested whether the Jabra headset with DECT can be registered directly with an external base station.