I don't think that CSR knew what he was talking about.
All previous Tivos have had a 7 day evaluation period. The Roamios should be no different.
Before activating, you should be able to fully set up your Roamio to the configuration you're going to use (cable card, etc.) and run though guided setup. You then should have limited functionality -- most features will be disabled, but you will have the core functionality of recording, setting up season passes, etc.
If you power up your Roamio and find that it does not have an evaluation period, refer to the following thread and try the suggestion in the first post.
Edit: I see that you already found that thread...