FWIW,
We are all more or less able to play another instrument. Not everyone can play enough of another ax to be worthy of recording it, but sometimes it's incredible how it can open your and your band mate's mind to change instruments.
We do that all the time when we record or rehearse.
I'm a bass player. I can play a bit of drum, and some keys and gtr.
The sax player is a fair bass player (plus he has this killa musicmaster bass too short for me to play on), he's a killer mandoline player as well
The guitarist is a good bass player but he's not as good mandolin as the sax (hehe)
the drummer can sing (LOL)
our singer is the best arranger of us all (plus she's my wife)
One day we exchanged instruments and realise that gave us something different but interesting. We composed a song just jamming like this.
Thanx to that, playing someone else part was NEVER a problem. We just passed the ego thing and we know that it is fairly possible your pal has a better groove for some strange reason. Never a problem. Only the result counts.
Learning to leave your ego at the door is often the key to interesting music.
as I said, FWIW
malice