Compatibility with PS1.6 from TB1.1.x
especially after the thirty bees fork diverges further from the PrestaShop code base; is that a valid assumption?
No, we are going to keep things compatible with at least 1.0.x
Is there any info about this argument?
Everything should be compatible in the 1.0.x branch. There are only two module classes that are not compatible that we know of, caching modules and friendly url modules. Those are not compatible because we have added them to the core.