Nice job!
I haven't noticed too many issues with my karat gold using either copperas or SMB, but I tend to use copperas on the first refine, SMB on the second. When/if I start doing higher volumes, I may switch to one or the other unless I encounter a problem, but it's working so far.
One last bit--if you're cementing your silver after you part it with nitric, you don't need to remelt it into cornflakes until you're ready to sell it or prep it for some other end use (realloying to Sterling, etc.). If you're just going to use it for future inquarting, you'd just be melting it twice by the time you alloy it with your karat scrap. Totally up to you in the end--just a suggestion.