**SIGH** Evan, Evan, Evan, please get your facts straight.

1. isa => "foo|bar" (used to work), now requires isa => "foo | bar"

Actually, "foo|bar" never worked, Moose just assumed it was some odd class name. And for the record, it works fine now. Try this with the latest Moose (using the oose helper module of course).

perl -Moose=Foo -e 'has bar => (isa => "Str|Int"); print Foo->new(bar 
+=> 100)->dump; print Foo->new(bar => "Hello")->dump;' ;
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I don't consider this breaking backwards compat, but fixing a bug.