Uh, sorry - that's a bogus argument. EU:MM works now for every stable Perl (5) version, out of the box. This is something that Module::Build cannot and will never^* be able to claim. There is little reason to "extend it" beyond the vanity of the Module::Build authors. Module::Build is a good idea followed by a long sequence of bad decisions and I get tired of people touting Module::Build as the bees knees. Those people are mainly the authors of Module::Build, who refrain from realizing why Module::Build hasn't seen the vast wave of adoption that was proclaimed when the project started. It may be cool for the maintainers of Module::Build and it might offer many benefits for module authors, like specifying what license your module has, or what testing dependencies your module has, but for the majority of people, the module users, Module::Build is just additional hassle, especially if it's not already.

Module::Install is no additional hassle for the module user and even has an auto-upgrade method in case the module author distributed an old/buggy version of Module::Install and you want to use a newer version. It caters to the module user at least as much as the module author, and it circumvents the whole compatibilty and installation crap that Module::Build has (had to) fight.

^* "Never" as in "as long as there are operating systems that come with a stock Perl with a version less than 5.10. Which will be for the next five years at least.