The autotools version only impacts people who want to build from Git.
If you are building from a release tarball it shouldn't matter what
version of autotools was used to create the release tarball.
Good point; in that case I don't have a preference.
Is there some Solaris build system where a prerelease tarball would be
submitted to test whether this will be a problem?
I don't know. I would go to opencsw -> navigate to gnu make. That page lists the current maintainer(s) of the gnu make build they provide as well as links to the makefile they use. I bet there's a way to contact them from there.
-brian