clever idea for BC with package.xml 2.0?

Hi, I've just added code that would allow a .tgz package to be bundled with both a package.xml version 2.0 and version 1.0. This means the installer would first look for package2.xml, and if it finds it, ignore package.xml. This will allow packages such as the PEAR package itself to provide both versions, to allow users of crap-old versions of PEAR to upgrade to any future version of PEAR 1.x, and will give the delightful ability to separate PEAR_ErrorStack out in PEAR 1.4.0 with no adverse side effects. My question: does this sound reasonable? Obviously this would also allow channels to distribute packages that will install with both older versions of PEAR and the latest version. With the old way of doing things, once you distribute a package in version 2.0, you shut out every single existing user of the PEAR installer. This isn't such a bad thing for most channels, as I expect channels will be primarily used for PHP5 apps written from scratch, but for existing infrastructure such as Horde, I imagine the existing userbase would crucify anyone who did that to them :). Greg