I know the Gentoo init scripts clean /tmp by default on each boot anyway. My developer laptop now has 32GB of ram and 32GB of swap (which my OS rarely uses), so there's no good reason not to do this.

Edit: one thing I did run into, back when I was trying to deploy DC/OS on DigitalOcean:

http://penguindreams.org/blog/installing-mesosphere-dcos-on-...

If you scroll down to "startup issues," you'll see that by default, /tmpfs is given half of the size of your total available memory. For starting DC/OS on really small DO nodes (it is a memory hog), it would simply fail due to running out of tmp space.