With FBWFQ flows minimum bandwidth is indirectly based on the assigned weights to all active flows in the WFQ system.
With CBWFQ you directly specify a minimum bandwidth per class.
With CBWFQ you need to bring your attention to bandwidth per class rather then weight.
Once you assign/create traffic classes then your next step is to allocate bandwidth per class using "bandwidth" command. After it happens your total link bandwidth will be proportionally allocated between your classes according to allocated bandwidth per class.
With Flow based WFQ your weight = 32768 / (IP Precedence + 1), because FBWFQ is ToS aware.
The figure 32768 also depends on IOS version on your router.
Hope this help you.
Regards,
Vakhtang