Use a .0 version of any software? You've got to be kidding! :-)

In all seriousness, I only use 5.10.0 when I'm wearing my cpan-testers hat. 5.8.x for everything else. Indeed, I only very recently upgraded my main machine from 5.8.3 to 5.8.8. I was pleasantly surprised that when I did so all the modules that I'd installed into /usr/local/lib/perl5/site_perl/5.8.3 were still available and still worked, even the XS ones. Thanks perl5-porters, you really are wonderful people!

Mind you, when I later installed new versions of some stuff in /usr/local/lib/perl5/site_perl/5.8.8, which had previousy been in .../5.8.3, it did show up a bug in some of my code that grovels over @INC to find available modules - it found things twice. Need to fix that. I wonder if it might be worth abstracting out that bit of code and uploading it to the CPAN on its own.