I only played a (Gibson) mandocello a few times years ago.

The owner originally had it in standard tuning but moved it to GDAD bozouki tuning.

As far as I was concerned, this particular attempt "ruined" the instrument. The joy of having the low notes was gone and all that was left was a (to me) clumsy feeling and nothing special sound wise bozouki.

I think he liked it though as he stuck with it...