It all depends on the printer. The Kinkos you went to more then likely does not pay attention to clogged nozzles or heads that are wore out. If you go to a Professional Printer the blacks will come out consistent. And to touch on the cmyk thing that also depends on the printers, some printers natively print at CMYK others at RGB, you will need to ask the printer what they recommend.
The image you sent will be a little tricky for some, they will need a good profile and not put too much ink down otherwise the subtle changes from pure black to a lighter black will get lost.
Scott