This idea to A/B test forms was also submitted in this thread. Perhaps if we can rally enough upvotes between the two posts, we can have HubSpot reconsider their decision to not have this functionality on their roadmap.
It would be a great help to be able to A/B test forms, and given all of the other rollouts HubSpot has made just this year alone perhaps they can add this one to the mix now as well, given that it’s been nearly 3 years since being asked for.