Thanks, David. I wonder if the 21x31 page trick would also work. I didn't have a chance to play with the printer yesterday, but will try it this week. I think there is also an option to scale to roll width, which may also work. If all else fails, I'll consult the 1000+ page manual.
Does Qimage produce visibly superior prints than the Canon driver? I'm a Mac guy, but do have a Win7 laptop I could use for printing.
Probably not. I haven't tested that with the 6300. I plan to do this soon. My guess is that Qimage in 8 bit printing will overall give at least equal results to Canon's 16 bit output. The last time I looked at this was on an Epson 3800, and Qimage was considerably better. It's not bypassing the the printer's driver, more like a better “front end”.
The main advantage for me is speed. I have all my printer/paper/output size/driver settings combinations set up as presets. All I have to do is select one (eg Ilford Gold Fibre Silk on 17” roll in monochrome with moderate output sharpening applied and a custom B&W profile applied and highest resolution) and Qimage sets up the layout and adjusts the printer settings. All I have to do is adjust the paper length in the driver if printing on a roll to match the print size. No double/triple checking driver settings. No wasted paper because I overlooked something.
Its print sharpening is good. It uprezzes on the fly and to my eye beats Photoshop and Genuine Fractals by a long way. Haven't tried Photozoom. Here it's also a question of convenience. If I uprez in Photoshop I end up with huge files, and considerable work to add enough grain to minimise artefacts and so on. Qimage takes about ten seconds to do a better job.
I don't want to give the impression it's the be-all and end-all for printing, of course it's not. But it suits my workflow.