Sparring with shoes isn't only realistic, it also improves traction.
Shoes. When ever I spar bare foot I sweat too much and slip.
I would put shoes on.
Why? It gives more stability and balance.
Barefoot you have a higher chance of twisting your ankle suddenly.
But with shoes your ankle's are protected a bit wich means less chance to twist thus less chance to fall
Barefoot. If I'm kicking, it makes things safer for my training partner; if leg locks are allowed, it makes things safer for ME.
The competitive formats I train for (MMA, submission grappling) are barefoot most of the time, anyway. I'm actually training in a way that's appropriate for those environments.
We always train in our bare feet, out side or inside. Just feels more natural plus that is the way we have trained for many years.
Barefoot all the way. More natural, traditional and much safer!
I prefer with shoes on.:)
Or if the place where you trained doesn't allow shoes, would you spar in shoes if they let you?