AD9834 B or C grade

Hello.

I have a project with AD9834BRZ used in. DDS is driven by 75 MHz. But in datasheet found 50 MHz MAX declared in ordering guide for B grade. The only differencies i found are currents of power supply and narrow band SFDR. Does it mean other dynamic parameters should be the same for B grade and C grade when clocking them with 75 MHz? SNR and THD noticed for both grades at 75 MHz clk.

Or should i to pay more attention to datasheet data? 

Thanks.