Opposite view: over the years I simply did a quick roughing of the original powder coat with #220-400 sandpaper and did all subsequent re-coloration with spray paint. We found rattle can touch-ups a good deal cheaper than re-powder coating, and done with a little care, looked just fine.
Realize that many/most shops use a "burn off oven" to get the old powder coating off. "Depending" on how hot they get it, this could "possibly" slightly change how the chassis flexes or yields.
My business was next to a powder coating shop for nearly 20 years, and I can say with certainty that burn-off ovens are not always precisely controlled (temperature and duration). Your mileage may vary.
Years ago I bought an Invader chassis that had paint that was like iron. Not knowing that much about paint, perhaps I could get some recommendations for paint that is really strong. Beauty is not the concern.
I used to coat frames for a very well known builder in the NE, but I can tell you we NEVER burnt off old powder, that is a major NO-NO on a chassis and will slightly alter the properties of the Chromoly tubing and flex. I always used a chemical stripper dip tank and then cured my powder at 375*F MAX. Those guys with burnoff ovens will let the temps exceed 550-650* and that WILL alter the characteristics of the tubing.