I never intended to choose a different format. I wanted to change my camera body to a different model - upgrade the processor, and maybe another 300mm with Vr, but you know how it is. YOUTUBE. Watching Mike Lane, Samuel Ruso, Peter Forsgard and others got me thinking. Initially I thought that the equipment that I was using was pinning me down. The problem with fast lenses, is that they are big and heavy. You also invariably need a tripod, and apart from the weight and size, you are restricted in where you can set up. With the Olympus system, because the lenses are made to be used with a smaller sensor, they are lighter and easier to transport. Coupled with the fact that the 300mm F4 (which in effect is a 600mm), and that the body and lens both have VR, apart from hide work, the tripod becomes redundant. No more heavy Benbo and Gimbal head. As my hands have always been shaky (and never improving) Vr for me is a necessity. Being Mirrorless means that shutter speeds per second is way higher. Up to 60 fps - compared to 8 or 10 with my DSLR. And then there's Pro Capture. This creates pictures before you anticipate the action- say a bird flying off a perch - before you finally press the shutter. A buffer is created and set to memory prior to your finger pressing down. What about the smaller sensor? I never bothered with 'Full Frame' anyway. I have always had APC size. It appears that most of the leaps in tech improvements, as far as image quality are concerned, have been made to cameras at the moment. It is software that has been radically improved. Noise is not an issue with packages such as DXO pure raw and Topaz denoise. If you need big files, the Gigapixel and other packages that are part of Photoshop etc. can increase. Above all, its the maneuverability that appeals to me. It was physically impossible to carry all my old kit. It was in two bags anyway - and that's without a tripod and Hide. All in all, so far, there's no complaints, and a lot of fun.