Thanks Rfortson, like I said, I have a sweet spot in my heart for Olympus. I may see how the systems from Olympus and Panasonic develop over the next few years and then give it a try.
As for "why working pros use Nikon and Canon" discussion, I think it is actually more complicated than most people think, in that a lot of professional photographers use what they do for reasons much different than independent purchasing decisions. Quite a few of them, if they work for agencies or newspapers, don't own their own equipment, and I would think they're probably glad that they don't for all the abuse that they put their equipment through
The reason this is important is that Nikon and Canon cater directly to these markets, even using reps to work directly with newspapers that are making the purchases. Even if Pentax had an equivalent offering in terms of camera and lenses for photojournalim, they wouldn't be used by the majority of working photojournalists. Why? Because Pentax does not have the sales or service infrastructure to compete with Canon and Nikon.
I'll give you a few real life examples. I know a photojournalist at one of the larger newspapers in the state. The paper, like most, has a relationship with Canon. He owns some Nikon lenses, and would prefer to use a D700 for his independent wedding work. However, ironically, as a working photojournalist he doesn't make enough to buy his own full frame gear. So he uses the Canon stuff for the weddings as well.
Another photojournalist I know, who left the industry for wedding photography when she moved back home, had to borrow camera equipment from her boyfriend when she was getting started. Her boyfriend worked at one of the biggest newspapers in the country, and, like most newspapers, this paper has a relationship with Canon. She also originally used Nikon, but after using the Canon equipment at several newspapers she worked for, she decided she liked it enough to buy her own.
See where this is going? It's not just that the Canon and Nikon systems have some advantages, which they do or I wouldn't have started this thread. It's that they have so greatly saturated the market that it's hard, even for giants like Sony, to break in.
Oh, and why don't these photographers do the honest thing and start off with smaller equipment first, maybe even with a comparably cheaper brand like Pentax or Olympus? Snobbery, hahaha. And because when they can use the more expensive stuff for free, they don't have to.