Printing photos — inkjet, laser printer, or photo lab?

I couldn’t tell, every high-end lab I deal with insists on RGB files, not CMYK separations. I haven’t worked with CMYK since the early 2000s. You would have to ask the lab itself. When I dealt with CMYK and newsprint, yes, there were definitely advantages to doing the separation yourself, especially when it came to the black plate and giving yourself more control staying within your ink limits. I don’t know of anyone who does individual color separations themselves for photo printing, though. There are posters here much more knowledgeable about this end of things. I’m thinking cmyk may be one of them.