Tbh, I hear that m205 isn't the ultimate finishing down polish.... but with your picture, it looks quite good and I would be happy with the m205 finish.
Maybe it could be that in your conditions (sunlight, heat, humidity, etc) m205 simply worked much better.
One thing for sure, this was an interesting post. Thanks for posting!
Do you mind if I copy your thread to autogeek and ask there?