Here is a link to some extensive early benchmarks.

https://www.phoronix.com/review/rasp...i-5-benchmarks

It's a massive performance increase over the existing RPi4. And as you said, the new in-house southbridge has really helped it.

Regarding PiStorm, I've been told they have no plans to support or utilise the RPi5. One reason being that the Amiga can't see more then 2GB ram (32bit address limited I'm assuming). Shame with such a performance increase.

It has got me wondering if the RPi5 would be the perfect hardware for the future of AmigaOS. They keep plowing on with tunnel vision with PPC. It's a dead technology and most are not prepared to pay silly money for proprietory motherboards. AmigaOS running on the RPi5 seems like it would be a great solution.