Cool, that's awesome info. You can basically tell how an amp will perform based on those key points of information. Maybe off by 10-15% based on different designs and what the ACTUAL rail voltage is inside the amp but it's always close.
For example, here I have an old SPL Dynamics amp, EXT-3000D it's the same exact thing as a SAZ-3000D. BUT, it has a little higher rail voltage, about 15% higher. It should do about 15% more power but really that's a guess because of limitations of the rail caps and other small issues and that's probably not worth any difference in price to most people.