I use QImage to print. But, much to the dismay of its author, I only use it for layout - not resizing, color management, or sharpening. (And, also because Photoshop doesn't allow printing without color management anymore.) I want the process to be fast. I don't want to wait for my computer to recalculate resizings, color transformations, or sharpening it's done before. And, I don't want to be able to make a mistake on which rendering intent or amount of sharpening I used in the past.
So, I prepare a "ready to go" TIFF file for QImage. I do the enlarging and sharpening in Photoshop (or PhotoZoom Pro if needed), and save as a gigantic file. I convert to the output profile, using the rendering intent I want to use. Then, in QImage, I turn off all color management, interpolation, and sharpening.
My time is limited, and storage has become very cheap. Others may strongly disagree, but I'd rather have a 1GB TIFF file sitting around ready to be spit to the printer and know for sure it's going to come out just like it did last time, and without having to wait for my computer to re-render it. (A 4TB drive is now around $185, so a 1GB file costs $0.045 to permanently store, plus backup costs - yes only 4.5˘)
I operate on-demand for many clients, and need reprinting to be as time efficient as possible. And, most of my work is artwork reproduction which starts out at 400ppi at original size anyway, so I'm already working with gigantic files.
So, I'm constantly converting to output profiles. And, what I'm considering a "bug" or at least a missing "feature" causes lots of problems then, because it isn't displaying accurately.