Dont agree - The body you use has a considerable effect on the handling of larger lenses and the feeling of balance will be greatly affected if you use the smaller M43 bodies compared to the larger ones
Although the 100 - 300mm is small in comparison with other formats it is still quite big on a micro four thirds body
It will handle much better IMO on the larger bodies and/or the ones with a good grip such as GH3/4, EM1, EM5 (with accessory Grip fitted)
Regards
Rob
I am a full-time working photographer, and use the same lenses on the smallest Pen bodies as I did on the largest pro-grade DSLRs, handling them every single day throughout the entire day. In my experience, I have felt no difference in how I handle large lenses no matter what body I use. The only difference I have found in using a larger, heavier, metal-framed DSLR body is in using smaller lenses, as there is a point where the lens is so small that you don't need to hold onto it, but can hold onto the body itself. Just like using pancake lenses on a compact body. The point where a lens falls into that category is the only difference in handling a slightly larger lens on a smaller body, but when using a super-tele there is no change in HOW you hold it, as you are already holding the lens. The change is that lightening the back end where you no longer carry your weight will make wielding that big mother around all frickin' day a lot easier and less taxing on you. That's a plus for the smaller body, as there were many times in the past where my arms would be totally spent after a day of shooting with big fast glass... and I am a strong man.
Now you are certainly free to disagree with me. There is no "yes or no" right or wrong answer, as there are many variables to be considered. The point I am bringing up through my varied experience is the importance of a variable which you are perhaps not seeing, which is that if you are having trouble handling your large lenses on a small body, then the problem is not in your body and lens combo or anything to do with your equipment, but rather in the technique of the photographer. Try hauling some of these 1KG+ lenses every day all day long, and you will learn how to handle them differently. What I am giving you is only advice, and you are free to dismiss it but please do not take it offensively... but good technique in handling large lenses will not only negate any differences in body size, but will also make your handling of super-telephoto lenses much more secure and steady. When you are using a long lens, try holding it at the very end of the lens when you release the shutter, instead of at the middle, and see how much of a difference it makes to the stability of your shot.
My overall suggestion is to stop worrying so much about "what your camera can handle", as it can probably handle a lot more than you you think. Worry more about adapting your technique as a photographer, and getting used to using different types of equipment instead. If there is something not right about how you're shooting for the equipment you're using, then learn to adapt to it so you can grow in skill.
Now I will add that there is one point in which the small body becomes bothersome with longer lenses, and that is when mounting the camera to a tripod when you are in that no-man's land in between a tripod collar and no tripod collar. Once you mount a tripod collar on your lens then the light weight of the body once again becomes an advantage, but when you are at the cusp with a lens that doesn't include a collar (since the decision to include them or not was largely based on a heavier body), then the small body will make for an unstable tripod mounting experience. There is a 4/3 adapter for some of your larger digital lenses which has a tripod mount on the adapter, and I would like to try that out one day.
I shoot mostly hand-held so this hardly ever affects me, but when it does this is the only place I am bothered by the small size of my bodies. Every other time I'm loving the reduced size and weight.
