Thanks Stephen for this crystal clear explanation. Really appreciate that.

I think it is possible to overcome the first limitation by paying Odoo SA some money - can someone confirm this ?

Kurt, I asked them and they said no. The only way would be a full paying customer. You can't just pay for that feature. sadly.

Can I use my own domain name?

Yes, we can set up your own domain name for Odoo Standard or Business (paid subscriptions only), e.g: www.mycompany.com. We can also manage email addresses.

I'm not so sure Kurt. I contacted odoo support on July 10th and was told by Richard Mathot that "The custom domain feature is available for paid subscriptions only ('Business Packs' or 'Standard Pack' with > 2 users)." I would be happy to be wrong so please contact support and report back. Not sure they want the same question from me again.

Another thing about the 2-users-4-free account is ... once you might be growing out of it can be tricky to migrate to anything else then the saas. An example: odoo 8 stable and saas-6 are identical. But as soon saas-7 comes along, and you are being migrated to it (which happens automatically on an saas subscription I guess) the database you will be running then will not fit an odoo-8 stable anymore probably. So, you can not just easily backup your database and restore it on any (local) odoo-8 server. You have to back-migrate to it, so to say. I'd say that is also a limitation one should be aware of.