The only "messing up" that might occur is if you take advantage of the increased storage and go beyond what a Plus account can handle. I've been Pro for years and am still well under the Plus limit, due to careful asset management, so that might not be an issue. Nothing else should change for you, and if you decide to revert to Plus, all assets, features and games should be as they were. If you exceed your Plus storage quota, even that stuff will all still be there and available. You just won't be able to add anything new until you delete enough to bring you back to under your limit. As an aside, I suspect you won't want to switch back. The API is very seductive...
