Bold statement but first some background: I shoot with a group of 7 or so photographers and we have monthly shoots with models at the beach, in the mountains, in the desert, all in very bright conditions, or in a studio. (I Luv LA) Funny that we all mainly shoot Nikon, there are 3 D800’s, 3 D600’s and 2 D700’s in the group, although an occasional 5D Mk II shows up. I am the only one who has ventured into M4/3, having bought a OMD-EM-5 about 14 months ago and I have used it alongside my D800 at many of the shoots. Shooting usually noon through sunset, I use the Sunny 16 rule for my manual outdoor exposures. In case you don’t know what the Sunny 16 Rule (*1) is, it is an exposure guideline for film, but still works great to this day with digital. With my D800 at ISO 100, I can shoot throughout the day with my Nikkor 85mm AF f/1.4D, 105mm f/2 DC or 135mm f/2 DC, all at aperture f/2, in the brightest sun at 1/8,000 shutter speed, all the way to sunset at 1/125 shutter speed (*2) without changing the ISO or f-stop, and pretty much get the perfect exposure. I don’t have to worry about overexposure, ND filters or other items to cut the amount of sunlight. This makes manual exposure so much easier, as the only thing I have to change, unless I want more depth of field, is shutter speed. Unfortunately at the base ISO of 200, the EM-5 has a more limited range, 4 stops, in the same situation as above for accommodating different lighting conditions. At 1/4000 shutter speed and ISO 200 the widest f/stop available, without over exposure, is f/4 (1/250 ss to 1/4,000 ss = 4 stops and f/16 to f/4 = 4 stops). F/2.8 would need 1/8,000 or ISO 100, neither of which the EM-5 has. My D800 has a 6 stop range and can go to f/2 as shown above. The D700 and D600/610 have a 5 stop range to f/2.8, even though their base ISO and maximum shutter speed are different, they are overall equal. And Yes, using ND filters will adjust the stop range, but in equal terms for all cameras. (As will higher ISO, VR lenses, IS lenses or IBIS when shooting in darker conditions, but these don’t help in bright sunny conditions.) To put it another way, with my EM-5 vs the D800, since the lowest ISO is 200, a stop is lost, and another is lost due to the 1/4000 maximum shutter speed. Thus for shots in bright sun, and to avoid being overexposed, ND filters, scrims or other items must be used to cut the sun and make up the lost 2 stop difference. All require forethought and setup and take away from some of the spontaneity of shooting. Couple of my buddies just look at me, shake their heads and say “why don’t you just shoot with the D800?” OK, so why is the EM-1 a game changer? Because it has the same 6 stop range as my D800!! Yes 1 stop is by going to the Low ISO 100 setting, which is kinda fudging, but from what I have read this is most likely where my ISO will be set. This and the 1/8,000 maximum shutter speed adds 2 stops to the EM-1 vs. the EM-5. The ability to shoot with my OLY 45mm 1.8 and 75mm 1.8 lenses at full aperture (technically at -1/3 stop exposure compensation) in full sun without filters or scrims, just like my D800 and 3 fast Nikkor primes, is a game changer for me. This is why I am upgrading to the EM-1. There are other reasons, the improved controls and buttons being next. But having seen posters here say the 1/8,000 shutter speed and ISO 100 is no big deal simply have not shot in the conditions I have. * 1 - Sunny 16 Rule. The rule, updated for digital, is: on bright sunny days (EV15) for the correct exposure of the subject at f/16, the shutter speed should be set to the reciprocal of the ISO. Thus for ISO 200, your camera should be at 1/250 shutter speed (1/200 actually, but not all cameras can deal with 1/4 or 1/3 speeds). For an ISO 100 setting, it would be 1/125 shutter speed. From this starting point it is easy to adjust shutter speed or f-stop to accommodate different lighting conditions. Cloudy bright light -2 stops down (EV13), full shade -4 stops down (EV 11), Las Vegas at night, outdoor night baseball, football games, campfires, 7 stops down (EV 8). ISO could be used too, but I shoot at the lowest ISO possible. BTW shooting the D800 and 85mm f/1.4 at 1.4, and not f/2, ads a full stop and its range becomes 7 for darker conditions. Gotta believe I WILL be in line for the Pany 42.5mm f/1.2, even though I love the Oly 45mm f/1.8. *2 - When shooting with longer lenses I like to use another old, but golden, rule for shutter speed of: keep the minimum shutter speed at the reciprocal of the lens length in mm. 85mm or 105mm should be 1/125 shutter speed for example. When shooting at f/2, with such a narrow depth of field, the slightest movement on my part, or the models, and the shot has lost sharpness. For this reason, I try to shoot models at 1/250 shutter speed.