I love the sound of instruments in the mandocello range, though I do wonder why Gibson style mandocellos are customarily strung with such heavy gauges. I often play a 10 string 650mm scale instrument that the builder and I refer to as a cittern, but on which I've settled on unison tuning, CGDAD like a mandocello with an additional higher course.
After some experimentation with gauges, I have 0.060“ phosphor bronze strings on the low C course, as lighter than that was too low tension, and going heavier was powerful in the low end but tends to be thumpy and not sound sweet higher up the neck. And many guitarists using open tunings with a low C are using no heavier than a 0.059", yet the available mandocello sets are 0.070“ or 0.074“ on what's essentially a Gibson guitar scale length. No wonder people find them hard to play!
The picture is from an earlier experiment with octave courses, though I've since kept it in unison.