NFS diskless was easier for me to setup when I was doing it.
THe caveat was, you needed readonly root, so that meant freezing the OS, anything that needed changing was either stored in a ram disk (that you need to setup) or a per host nfs area (kinda like overlayfs, but not)
Why would you need a read-only root? Do you mean to share across multiple machines?
Yeah it makes things a bit easier to debug. Originally my system was designed to run on multiple machines at once.
If you needed to update the root dir, you chrooted into it and did the (yum) update.