I have been flying with a Nano 4 for the last couple of months. Impressive little unit with a very clear bright display. It has made my LX5000/PDA set-up virtually unecessary because the final glide computations are virtually identical. Great when I am flying the club trainer which has no electronic instrumentation. Have it attached to my instrument panel with Velcro and in flight the buttons on the front give positive inputs. On the ground, the touch screen make navigating the screens and inputting info very easy. I have looked at the Colibri X which is also a solid, well built little unit. Looks similar in functions to the Nano 4. Touch screen only though. I think it's best to view both and then make your choice based on your personal preference. Both look fantastic.