I print through the Canon Plug-in with 8300 and do the layout in Photoshop. I used to use ImagePrint on my Epson 9800 and while the proxy layout in that program is quick and convenient, the quirkiness of ImagePrint seemed to negate much it's value as a speedy alternative to doing a layout in Photoshop. A couple of big pages have been a slog, such as laying out eight 5"x110" strips of 16 bit 300 dpi images. Photoshop slows down mightily on those! Most of the time, on pages 44"x36" or smaller, layout of multiple images is not difficult.
One other advantage of ImagePrint was that multiple pictures did not have to be of the same resolution or color space profile to lay out, but they do have to match when laying out a large page in Photoshop.