Here we go: a final version number.
I consider mxdev now as stable. I used it in different scenarios and it just works (for me 
).
- It now supports different modes of pip source install (skip, direct, interdependency). Latter was first tricky to figure out, due to pip's strict behavior. It is needed if you develop lots of packages with dependencies between them - and don't want to care about installation order yourself.
- as a new feature it can now override versions from an upstream constraint. pip does not allow to redefine a version constraint - preprocessing helps here too.
- Fine grained defaults can be defined.
- In any case, in the resulting output files every change made is transparent and easy to inspect.
That said pip is a great but very strict tool. First I was a bit angry about it. No I no longer think this is a problem, since we can preprocess everything into an well defined description and then run pip. In fact strictness helps to get things well defined and right.
The mxdev sources.ini defines the changes to a current (upstream) configuration, like a Plone release. Then both is processed and turned into a new well defined configuration. In fact it is a transform.
All three parts - input, declaration of transformation, output - are well defined and transparent.