[Mandobart]

I'm not the best judge of difficulty. I started on violin when I was 10 and guitar when I was 13. I started mandolin in my 40's. Mandolin is tuned just like a violin, in 5ths GDAE. Mandocello is an octave and 5th lower CGDA (just llike a cello).

Because I played violin and was used to picking guitar, I was instantly playing mandolin from the moment I picked it up. When I decided to play octave mandolin (just a whole octave below mandolin) the only adjustment was a 21" scale vs 15". When I added mandocello the scale expanded to 25" and I added a low C and dropped the E.

So it was an evolutionary progression for me.

Going from guitar to mandocello, the first thing is the extra stretch. On guitar the 5th fret on one string brings you to the next open string. On the mandocello its the 7th fret. Chords are completely different. You can do a lot with just 3 or even 2 course chords. Lots of moveable shapes too. And the 5ths tuning is intuitive and symetric - a C chord on the A and D strings becomes an F when shifted down (lower) to the G and D. Move it down to the C and G and its a Bb.

To answer your question - if going from guitar to ukulele is a 4, I would rate going from guitar to mandocello an 8.

You'll find uses for your pinky you never needed on guitar.

Also, tenor guitars are often tuned CGDA like a mandocello.