I strongly disagree with this point. Patching in bug/security fixes to different versions of a product is several orders of magnitude more work than just having everyone on the latest, most secure and most patched version. For a side project to be successful you want to spend as as little energy on admin as possible and much energy on the project as you can.

Have one version. Differentiate between tiers by using feature flags so everyone is on the same codebase. Make development easy and design things so there's as little admin work as you possibly can.