Thank you! That's a very valid point and we've seen this with customers quite often: the thought of changing the whole underlying layer can (understandably) scare people.

We've built a (soon-to-be-completely-)automated process of converting Google Tag Manager containers to Zaraz, and that helps a lot with convincing customers because everything Just Works without them needing to do anything (we also hook to their dataLayer events). For other tools it's still a work in progress, but in general we convert whatever stack a customer has to Zaraz as part of the onboarding process. Honestly that's one main reason why we don't yet offer a free tier.