Another thing to take into consideration (other than noise), is that the higher resolution sensors (in smaller physical sizes) seem to have a habit of suffering from higher than average purple fringing in some conditions.
Why is another question entirely (unless it has to do with the small size of the photosites for each pixel, with the microlenses acting as a contributing factor).
Of course, you can also get Chromatic Aberrations on a DSLR model (depending on the quality of the lens used). But, the 8MP models (so far), using a Sony 8MP 2/3" CCD,seem to have much more of a problem with this phenemonen compared to themodels they replaced (usinga Sony 5MP 2/3" CCD)..
So, if you're taking photos of high contrast areas (i.e., tree limbs against a bright sky), then this is something to take into consideration if you need large prints.
The other thing I'd take into consideration is Dynamic Range (ability of the sensor to capture both light and dark areas of a scene). Although I haven't seen anybody measuring this, to my eyes, the sensors using smaller photosites for each pixel seem to suffer from lack of dynamic range, compared to the DSLR models using much larger sensors.
I'd probably wait until the camera has some decent reviews (and lots of user photos) before making any judgement on image quality.
One other thing to consider is your ability to control Depth of Field via Aperture. With a non-DSLR model, it can be difficult to make a subject stand out from a background by using a larger aperture (because the actual focal length of the lens is too short; and depth of field is based on actual versus 35mm equivalent focal length.
Of course, for Landscapes, you're usually looking for more (versus less) Depth of Field, so this part could be considered an advantage for the CP 8400, since you wouldn't need to stop down the aperture as much for greater depth of field (but a big disadvantage if you're shooting portraits, where you'd want a shallow depth of field to help your subject stand out from the background).