Paul, it seems to me you've got a pretty good idea about what running an OpenACS business involves. About your two concerns, I think that if you have clients already this is all the proof you need for believing that OpenACS can be traded profitably (not that I would know...). (1) The GPL is actually not a problem; since you'll in fact be selling services and not products, it doesn't matter if the product is free. (2) The GPL is also the essential reason why there is a good chance that your business will succeed; because the code is free, you and your clients won't have to invest money in the product you offer but only in your work skills.
You're also asking about the community standards, that is, how the community expects OpenACS companies to behave. This issue is rather central to OpenACS professionals, and it has recently been addressed in another thread. There's no explicit statement on what is customary or accepted behavior, but in practice the norms are set by the OpenACS leadership (which is quite natural in an informal meritocracy). Adherring to the (implicit) community standards may in fact be the real key to running "stable, profitable, longer-lived businesses". That's why the dotLRN boards has begun to take an interest in stating these norms.
