I never interpolate images for print. In fact I often accept 150ppi
for a large print size (23"x35") as opposed to interpolation.
I don't plan to get into any interface or workflow debates but I do want to point out something with respect to the above comment. You may not overtly be doing any interpolation but it
will be done by the driver if you don't! If you have an Epson printer, for example, your driver will most likely be running at 720 PPI and the dots will be placed on the page at 1440, 2880 or some multiple of 720. If you are using a Canon or HP, the numbers will be multiples of 600 instead of 720. Unless your image is already
exactly 600 or 720 PPI right out of the camera/scanner, the driver will do its own interpolation to get it to match a multiple of the final print PPI. The question here is: do you want to leave this important step to a print driver that uses undisclosed (and sometimes quite poor) interpolation methods? Most of the time, depending on your image and what size you choose to print, you'll be starting with a completely arbitrary PPI like 227 and your final print will be a multiple of either 600 or 720 PPI, so by definition, interpolation is happening somewhere! You might as well take control of it to make sure you get the best performance.
The second point here is that Qimage gives you so much control over
how you print that you can turn off all the interpolation, sharpening, and antialiasing if you like. I wouldn't suggest it but if you are so adamant about just letting the print driver do the interpolation, it can be done. At that point, Qimage is still useful in that it allows you to do gang printing very easily and be able to save/recall all your settings and even old print jobs. You are not forced to use interpolation if you really want to leave it to the driver.
My only comment on the interface is that most people arbitrarily assume that the interface is "clunky" because it has a lot of buttons and controls. Not so once you learn to use it because those controls are necessary in order to give you the power you need to do
any print job. If you don't need that much power, you can always get Qimage Lite which has a much simpler interface for those who don't do complex jobs and it still offers the same print quality. And let's face it, PhotoShop is not very intuitive either when you first start to use it. It's very easy to get lost in its spider web of nested menus and popups. That's why people make careers out of teaching people how to use it! The only reason it is more accepted is because people have gotten used to its terminology and arrangement of functions over time.
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Mike
Author: Qimage, Profile Prism
http://www.ddisoftware.com 
