If you look at max sum of breaker stab, it may be below 200A. Many of the stab ons are rated at 145-165 max sum of each stab, due to either the reduced contact area of that type of breaker, or the way the buss-work is cut and bent, might reduce cross-section.
GE has a really small contact area on stab breakers.
Murray/Siemens have reduced cross-section.
Older CH, and SqD QO just dont have either to make higher amperage CBs work out without burning the busswork.
Newer CH have bigger greased pads for contact on the stab in CBs in the 50 to 200 range.
Our PM just found out the hard way about this very issue, trying to get a 320/400 MM w/ 200A and another 200 out of the 200 distribution portion of a 20/40 in the same panel. (165A Max sum per stab)
FYI If you need CBs for feeders in the 100 -200 range you may be better off with bolt on's.
