I see your point... I've never upgraded to the non-LTS Java versions (almost no one is doing it - as you can see in any survey about it - which in itself is enough for me not to be the "brave" one doing it!) so I don't know how much pain that would've been.
To me that just shows that Groovy could do with a bit more attention as I find it to be a great language, specially with Spock... it has made our tests so much nicer. It does have some warts but those are mostly a result of the lack of attention it receives, unfortunately, not some fundamental issues with the language.
It is a bit brave to upgrade every 6 releases or every 4, I prefer to have smaller issues more often than big ones rarely.
But I get that most of the time the issues is with dependencies that upgrade to lazily (that's why I don't like those that are bytecode magic and don't use ASM).
