Once again I would plead for a bit of home science, or not really science at all, but rather simple testing. Otherwise we will need to create a new group called "Coffee Religion."
Nothing is simpler and of less value than creating dogma based on hypothetical explanations. In our case here it is just as easy to do some simple testing and come to "personally objective" results.
Just roast some beans, put part of them in a bag with valve, put part of them in a bag without a valve and part of them in the hopper. Use them alternately and see if you can tell a difference. It would be best to "neutralise" the test so it was blind, but that is probably too difficult. Be honest with yourself because it is only yourself you are fooling. If you can reliably taste a difference pat yourself on your back and store the beans the way you found best. If you can't taste a difference then you know it doesn't matter. Forget dogma.
That said, I have done the above and I'm with Zix. I roast 2 or 3 batches of 230g each in the HotTop, dump them in the hopper, let them degas for a day and then use them up within 7 days. I tried bags, I tried vacuum containers, I tried jars, I tried weighing the beans and putting 18g in the hopper, grinding, cleaning, etc. I have never been able to detect a difference between these various ways of treating freshly roasted beans.
The degassing time varies from one bean to another, but generally I find that within 18-24 hours after roasting most beans are usable for espresso. There are exceptions, of course.
Finally, as was said above, there are very good reasons for commercial roasters to use valve bags. They do not apply to home roasters or artisan roasters for a number of reasons.