Version 0.91 of the QCheck packages is now available:
Release 0.91 · c-cube/qcheck · GitHub
This release adds ocamlmig annotations to most of the renamed combinators, in an attempt to ease migration for users. From my experiments so far, these work pretty well and allowed me to port multicoretests with little effort. Thanks to @raphael-proust for the suggestion and @v-gb for a nice tool! 
Happy migration and testing! 