Dev beta and public beta are exactly the same (I’ll add the qualifier “99% of the time” to silence those who will inevitably remind me of the one or 2 times that was not the case
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). The only difference is when they are released to the respective groups. Early on, the public beta can be released a week or several days later. From here on out it should be same day, 2-3 hours apart.
Generally, I’d say things are pretty locked down by this point
BUT things can happen to individual users at any time during a beta process. If you are comfortable reverting back to the current publicly released version of iOS AND you’ve created an archived backup, you should be ok.