Originally posted by Homo_erectus When it comes to comparing the physical size and weight of different camera bodies, camerasize.com is very useful although it isn't always perfect.
Compare camera dimensions side by side
So for example, it's easy to see that the K3 and the X-T2 are about the same width across but the X-T2 is 10mm shorter, and the K3 is 28mm thicker than the X-T2. Also, the K3 weighs 58% more than the X-T2 (800g vs 500g). The KP has basically the same exterior dimensions as the K3 but it weighs 700g, or about 40% more than the X-T2.
The X-T20 weighs only 383g and that makes the K3 just over twice it's weight and the KP around 85% heavier.
I used this website extensively when I was on my quest to cut the weight of my equipment in half. Sadly, I never found an equivalent for lenses.
Originally posted by Rondec Size of the K-P is pretty close in height, but certainly it is thicker and a little heavier than the XT-2/
Compare camera dimensions side by side
I think it is important to remember that Fuji benefits from a shorter registration distance when it comes to wide angle primes. I don't understand the reasons for it, but lenses will be smallest when they are around the same focal length as the registration distance. This means that lenses around 18mm will be a lot smaller on the Fuji and around 40mm will be smaller on the K mount. I thought you mostly shot longer lenses, but if you are more interested in wide angles, than the Fuji will provide a smaller package.
Once you get to longer primes, like the FA 77 or DA 70, or deal with pretty fast zooms, you find that there is actually a bit of a penalty that you pay for those shorter registration distances. The Fuji 50-140 f2.8 weighs 995 grams while the DA *50-135 is 685 grams and is 500 dollars cheaper on B and H.
Anyway, I really think there aren't any bad cameras out there at this point. The thing is to use what works for you and what you enjoy using. I don't think I could go from Pentax ergonomics to Fuji and back again easily, but obviously plenty of folks do.
Short of going to micro 4/3 lenses (also a valid consideration), the Fuji lenses (apart from the 27mm) are nearly all faster, and therefore bigger, since they need to still cover the APS-C image circle.
Exception: Pentax has a gem in the DA 70, though, nothing to match it. I have the 60mm Fuji macro and it is sharper (and with better bokeh, too), but slow, large, and extends like crazy.
In terms of design, yes, you are right with the registration distances. If you are willing to forgo the 2/3 stop, the 50-200mm F3.5-4.8 is 580g, and focuses much quicker than the 50-135mm. The price is a lot nicer, too.
Like you say, nothing really in it though, some days I enjoy shooting Pentax, some Fuji, and some m4/3. If you shot (or shoot) film Pentax gear a lot, there is nothing really that different about the ergonomics to the Fuji. Processing is easier on the Pentax/m43 (with Lightroom), but not too different, except for ultimate sharpness levels.