That's really nice. I remember having to use Read-Only on a few Raspberry Pi projects because they have a tendency to corrupt SD cards. Getting a free storage performance boost would really improve usability for my past use cases.
On top of that I recommend industrial grade SD cards using (a)MLC. They might be a bit more expensive but it is worth the stability.
I learned this from these posts (among others in the same thread 'Raspberry Pi microSD card performance comparison') [1] [2]
Coincidentally, for those projects I did end up mounting to a tmpfs, syncing configs from a server, and writing them to a SPI flash chip with FEC. Fun to know that others suggest the same!
I was just thinking along the lines of performance improvement for the absolute garbage SD card speeds. I just remember how flipping long it would take to load a program off those things.