I don't know about how important EFI and reducing the bootloader technical debt is for
the project, but at least for me personally, it will be a straight way out. My hard disk
has a traditional MBR based structure with about a TB of very important data. I don't
know of a 100% reliable way of converting it to GPT. While I do have backup for most
important files, not everything is backed up nor do I have means to do so.
The system works perfectly fine for me and I see no reason why I should opt for EFI. What
is the value add for me, at least till I don't upgrade to a newer system? which I
won't be at least for next 2 years. So forcing such a no-value-add change to existing
user will drive them away. At least I would opt for a different distro in such case even
though it's not something I want to do.
I feel the better approach would be to use it as default for new installations, if the
disks are appropriately formatted or are empty at the time of installation. Else a fall
back to grub should be transparently done.
Just my 2 cents from a user's perspective.