To me, one of the defining characteristics of a mirrorless ILC--like the
Which is why I'm confused by the trend toward even smaller sensor sizes in this space as evidenced by Sensor Size Cheat Sheet.)with its 5.5x multiplier and the rumored forthcoming 2.7x-multiplier size from Nikon. (As an aside, I find the easiest way to internalize differences in sensor sizes is by the multipliers and assume that pixels shrink correspondingly. For a comprehensive visualization, check out this
Some people complain that even the Four Thirds sensor (2x), which uses the Micro Four Thirds mount in Panasonic and Olympus' ILCs, is too small.
In image quality terms, that means the Pentax will likely deliver image quality on par with other 1/2.3-inch sensor models like the
The drawback of the "larger" sensors, though, is that they require larger lens mounts with correspondingly larger lenses, so while the manufacturers can attain extremely compact bodies, when equipped with a zoom lens the cameras cease to to be pocketable. I think this is one of the biggest issues with Sony's NEX series, generally characterized by tiny cameras with huge heavy lenses.
So I ask you: How small is too small? How low would you go to obtain an ILC that, when equipped with a zoom lens, fits in your pocket? And as long as you're OK with a sensor that small, why not just get a compact megazoom with manual controls?