However converting a package with a more convoluted rules files
will take humanpower. While it may be justified to convert a mildly
complex rules file on a package that has some activity, I don't think I
would invest those resources to convert a package that's been working
for years without anyone touching it's rules files.
In the past I took the approach that nearly anything that required me to tweak it's build system more than flipping configure switches meant that the upstream build system needed _something_ to be more clever and do what I wanted by itself. That lead me to write patches that were then gladly accepted and therefore further simplified the rules file even more.
So I would tend to treat this change as any other (e.g. the quilt
format): on a best effort basis, whenever you have to touch a rules
file, consider switching
I did just that on several NMUs that I did: I needed to mildly touch the rules file, it proved easier to just rewrite it using dh :>