I've been thinking the same for two years, recently started a new project on java 5, and yes, it is better from a coding point of view. Brings more or less nothing to the final user, except better written code, which is not nothing at all.
+1
But again, for those users that have a strict need for 1.4, what about tools like http://retroweaver.sourceforge.net/ or http://retrotranslator.sourceforge.net/ which also have a maven plugin? I'm testing my java 5 application, retro-compiled to java 4, and it seems to work correctly.
It should as the byte-code itself is not really different at all. IMO an alternative worth thinking about. cheers -- Torsten