Looking at the SX7 manual it looks like you'll be ok.http://www.usa.canon.com/app/pdf/projector..._SX6_Manual.pdf
(yeah, that's the link that comes up for sx7)
In the back it shows you will be able to do the 1400x1050 over vga.
The SX80 has HDMI. This is the now and future video connection. The cool thing about this is for instance the 5d2 has an HDMI output so you could plug the camera straight in and show video or pictures from it. Not sure when your Phase One will have this lol. Most better video cameras these days also have HDMI outputs. The sx80 looks like it can also handle things just fine over VGA.
Really though, with it only costing $40 or $50 for a cable, pay up and get the DVI cable.
Of course maybe Apple doesn't have a DVI output, maybe it's some apple miniport, I'm a PC guy so I don't know. Still monoprice.com probably has the cable, or an adapter and it will be fairly affordable.
For a discussion on projectors, check herehttp://www.avsforum.com/avs-vb/forumdisplay.php?f=68
Not much on Canon there, since they're not into the Home Theater market. BTW, you have to sign up on the forums there to enable search.
Here's a thread there on cable runs, most are against vga at that distance, and they're nowhere close to as high a resolution as you.http://www.avsforum.com/avs-vb/showthread.php?t=773778
This will get you up to speed on all the different video connectorshttp://lyberty.com/encyc/articles/tech/vid...onnections.html