I looked at both printers too, some months ago.
First, I note that Canon has extended its rebate. Nice, but I chose the Epson anyway.
Second, reports are that the gamut differences are very slight - a technical difference that would not be evident in actual prints.
Third, don't minimize the size and weight differences - they are staggering. The Epson can be shipped via normal methods or loaded in your car, it can be lifted easily by one person, and it fits quite comfortably and even almost discreetely in a small home office. The Canon ships on a huge pallet, requires two people (minimum) to move, consumes a massive amount of space, and has a physical presence that will utterly dominate almost any home office. Given a machine that big and imposing, I'd be looking at a 24" printer!
Fourth, after buying an expensive printer and costly fine-art paper, etc., differences in ink use and costs are likely to be minor issues for a user with "relatively low volume" needs.
Fifth, by most reports, the Epson is a more mature system that has fewer glitches in its hardware and drivers. Edit: I'd be quite alarmed by the many reports of teething problems with the Canon. The Epson has been a totally trouble free experience for me thus far.
Sixth, as a previous poster stated, third-party support is likely to be much higher for the Epson, at least for a while.
On the other hand, there's no roll support for the Epson. That's a tradeoff with importance that only you can figure out. For me it was not an issue since I'm also a low volume user that has no interest in dealing with curl. I also note greatly increasing choices in large cut sheets these days, so I don't see it as much of an issue for me.
Also, on the other hand, the ink swapping is still not without costs. I've never quite settled the matte vs. glossier paper debate, and I'd prefer to switch papers without giving that any thought, but as a former 2200 user, I've long-since adapted to making that switch on a less frequent basis.
The bottom line is that the Epson is a very good compromise for a medium-volume home printer, whereas the Canon is intended as a no-compromise printer aimed directly (and perhaps only) at a higher-volume user that has a studio with more space.
I am quite happy with the Epson.