[xmonad] Multiple monitors of different shapes and sizes?

How (if at all) does xmonad cope with being run on a system with two monitors of different resolutions? The FAQ entry about multiple monitors says, if I've understood right, that you get one workspace on each monitor; so is everything in a workspace liable to get resized if it's switched from one monitor to the other, and if so how painful is that in practice? (I ask because I'm a happy but ignorant xmonad user, and am wondering about adding a second monitor to my machine, and can get one of a different resolution from my existing one much cheaper than one of the exact same resolution.) Thanks in advance for any enlightening advice. -- Gareth McCaughan