Looking at the DxO specs for the two cameras, most of us would be asking, what kind of lens can I get for the price difference? I agree with the above poster in that, when I put on my fisheye lens 10-17 lens, I'm looking for a niche shot to spice up a series of photos, very rarely are those shots in any way useful on their own. It's a nice compliment.
The difference in printing on these two cameras will not be noticeable. I don't think the human eye can detect the difference between 180 dpi and 220 dpi, not to mention that depending on your printer, it may end up printing at the same DPI anyway. When you talk about resolution you have to decide what is adequate for your needs. Are you really going to be printing a lot of 16x24 images?
My printer goes to 19x13. The lowest print resolution I usually consider is 150 dpi. I've had good results at 125 , but for some reason I try and stay higher. I'll reconsider when I see see research that says people can tell the difference from 3 feet away, because I can't. My old Optio W10 had 2000 pixels width and I have some great prints taken with it. The K-5 will print 33in by 21in at 150 dpi. If I need more than that, I doubt moving to the Canon 5D MkII is going to solve my problem. I'm thinking the next stop after 20 x30 is likely to be 48 by something, and the Canon doesn't get me there at 150 dpi. It gets me to 37 inches. You don't have to like the numbers I'm using, but for examples sake, it gives you the logic behind why I don't care much about the difference in size. For my shooting my K20D does fine.
So that brings us to the main difference as I see it, the K-5s extended Dynamic Range. I carry a range of zoom lenses from 10 to 300 mm so I don't worry much about the smaller sensor. I rarely like pictures shot less than about 14 mm unless the scene is such that it masks the distortion. The biggest issue for me is dynamic range. I've had more shots rendered useless by insufficient dynamic range than any other issue, even when bracketing. In some of those cases I could have gone HDR, but shooting something moving, like water, there can be issues, time consuming issues. The K-5 should have a clear advantage in Dynamic range.
So for me the issue comes down to, do I need that extra 12% resolution. I don't care on the sensor size issue, it's completely compensated for by the lenses you buy, and the smaller sensor extends the range of long lenses, so it's a six of one, half dozen of the other, the Pentax has a tighter pixel pitch, so it really does give you more pixel output using the same lens. I don't need the extra resolution, although some people might. The Pentax has better dynamic range at least in the DxO labs, which is a real plus in landscape where the contrast of natural light can be as much as 5000:1. And the Canon is 3 times the price, the difference being enough to buy me a really nice lens.
I really don't see why you'd buy the Canon, unless of course there's a Canon lens you have a preference for. Some old advice for camera purchasers, "Find a lens you like and buy the body that goes with it." So I'm not even sure you're barking up the right tree. Arguing about lens sharpness is pretty much a non-issue for the landscape artist. You have to ask, how many landscapes have I had ruined because the lens wasn't sharp enough. The minute differences may be important if you're shooting in a studio under controlled light. But I'm willing to bet, in landscape, a little bit of loss in detail around the edges? People sell painting that have almost no detail. No where near that of any camera. In landscape the overall splashes of colour and composition are more important than microscopic edge detail. The key thing here is finding a lens you like. That could become a full time job in itself for a month or two.