Atomically flipping a version is still difficult, as anything that needs to rely on the other version has to be fixed forward. If you instead make 5000 (or 500)

Atomically flipping a version is still difficult, as anything that needs to rely on the other version has to be fixed forward. If you instead make 5000 (or 500) small changes that affect 10-15 uses, you can solve the unique cases or roll-back and forward.