Hi Dist,
You are correct, a test channel will be able to successfully trigger bits-in-extension functionality without bits being consumed as long as the testing user is on its own channel and the extension is in a testing version. Our main reason for this change is so developers do not have to go to their affiliates or partners in order to test an extension.
In regards to your concern around get Products, you should be able to call getProducts from any channel. The call was restricted for a couple days when we introduced a new functionality but that bug has been fixed. Please let me know if you still encounter issues with that call.
setUseLoopBack functionality is specific to the helper and remained untouched.