[cpucycling]

By all means, have a separate, passphrase-protected key for each separate device (desktop, laptop, tablet) and push them to your machines using something like chef and the 'users' and 'sudo' community cookbooks, at a minimum, and destroy the .pem after you initially set up the host.

There is a reason that Amazon only configures one user with only one key, and it's not because that's how sane people access their machine.