Yes, good advise. It's easy enough to hard code the CBSubs plan ids. That way the user has ultimate template flexibility on exactly the plans for which they'd like to filter the Mosets Tree fields.
I am trying to make this Mosets Tree template as generally applicable as possible. So first before I dive into the CBSubs plan ids, I'd make sure the user has CBSubs installed. Is there an SQL query (or some other indicator) that will provide me a guaranteed TRUE/FALSE indicator on if CBSubs is installed?