My Acer C720-2802 Chromebook came with 2G RAM and a 16G SSD. I decided to upgrade the SSD to 64G in contemplation of replacing ChromeOS with Linux.
This was a pretty easy hardware upgrade.
I followed the directions here:
(checked this against the developer wiki entry for this model)
Since I’d already popped the back of this unit once (to remove the write-protect screw so that it could boot into Developer mode without intervention), there was no fretting over violating the warranty. It was already violated.
ChromeOS was restored from the recovery image I’d previously burned (followed these instructions)
All in all a very quick and simple improvement.