This is a really great idea! If you don't mind, I'll put this on a list of to-do features.

I was testing a "nudge" feature, where you need to move a mouse a little faster towards the other screen to have it jump across. It was not bad, even though I've found it to be most intuitive when the cursor simply moves freely like it was one big desktop.

Clipboard would be awesome to have, but considering privacy, security and data protection concerns, it's just too risky.