(4) And perhaps my most generic issue aside from (1). PEX tries to be everything for everyone. In failing to limit its scope, it generally does many things relatively poorly, instead of doing a scope-limited thing very well. I would prefer more boilerplate and constraints at bundle-time, up to and including encoding known information about my target platform like which interpreter I want to use, rather than have to make sure that I jump through the right hoops at runtime like setting environment variables or messing with PATH. (as one example)