Switching back and forth can be a real trick. If you are playing in full screen mode, the machine will want to drop out of that any time you click on the other monitor.
Large IPS monitors are also a bit tricky for gaming. Imho anything bigger than 27" is too big, you can't see the whole screen at once (though I have no objection to multi-monitor for peripheral vision).
However, 27" IPS panels haven't been tuned for gaming (their response times are bad), and you'll actually get better performance from a 30 incher.
For gaming, you want a panel with a 7ms or lower response time. In 24" Try a dell u24112m or an hp zr2440w (or zr24w).
If you go 30" try the hp zr30w. It's lack of an OSD gives it lower input lag while maintaining a...