That is very true. We use copy on write for exe.dev base images right now, and are accumulating a lot of storage because of version drift.

We believe the fix here is to mount the base image as a read-only block device, then mount a read-write block device overlay. We have not rolled it out yet because there are some edge cases we are working through, and we convinced ourselves we could rework images after the fact onto a base image.

Right now our big win from copy-on-write is cloning VMs. You can `ssh exe.dev cp curvm newvm` in about a second to split your computer into a new one. It enables a lot of great workflows.