ABCL is one of the three implementations, together with CLISP and CMUCL, where I ultimately punted on ASDF hot-upgrade, by just trying to rename away the ASDF package if it's too old.
I don't know if you're interested in making the kind of package surgery I was indulging in work, but it involves rehoming symbols from ASDF to subpackages such as ASDF/COMPONENT, including for class slot names.
Anyway, please test the latest ASDF with ABCL, I think it's ripe for release, but I'd like your feedback considering the massive amount of hacking that happened.
—♯ƒ • François-René ÐVB Rideau •Reflection&Cybernethics• http://fare.tunes.org If the human mind were simple enough to understand, we'd be too simple to understand it. — Pat Bahn