Help me decide on my keyboard

I have a Surface Pro and I sometimes feel like I really would need a wireless keyboard for it. I have looked at the K380 and K810, but couldn't decide.

I couldn't try them out, but the round buttons seem weird to me. A disatvantage are also the small up and down keys. Other than that, both keyboards seem fine. What would you advise me?

You can also give me other suggestions, but I would prefer if they all were under 30 cm.

Also, does anyone know if my keyboard and my Mouse MX Master can use the device switching feature togther? Like if I switch on one of them, will the other change too?