To me, it not entirely the lens selection, but more on Body Ruggedness with fast processing and great ISO performance to at least ISO 1600 before noise becomes something to deal will with in Post.
"A Pro Photographer" needs these 3 features plus higher grade lenses (More in the build quality over sharpness with some already available lenses).

Things like a medal under chassis, Medal body or at least top and bottom plates of medal. (light weight), internal parts made to a higher fit tolerance with longer lasting and tougher build. (tighter/better fit). External buttons with longer lasting electronic switches and better springs for longer wear....You get the idea...
The Build must be able take bumps and bruises and keep working.
Plus, a fast flash sync for outdoor fill flash at high shutter speeds.
Plus a fast Shutter Speed for wide f/stop shooting out side. (1/8000)

Everyone is talking about the forthcoming E-P3 as a "pro" camera, or hoping that it will attain this "level." But what does this really mean? According to a recent post on another site the standard against which m43 must be measured is the fast zoom:


"I am a current M 4/3 (Panasonic G1) user, and I shoot with Canon DSLRs as well.
My favorite Canon lens is 70-200mm f/2.8 - similar lenses exist in all DSLR families, and from Sigma and Tamron.
Of course, it's a huge / heavy lens. 200mm at f/2.8 requires more than 70mm front element diameter, and full-frame imaging circle keep rear element(s) large enough. A 4/3 equivalent would be 35-100mm f/2.8, with half of the imaging circle. Required front element will be 36mm - this lens would be not larger or heavier than Panasonic 45-200mm. Why nobody makes it?
More importantly, does this mean that Panasonic and Olympus see Micro 4/3 as exclusively consumer-grade system, so no fast zooms will be ever made?"[/b]
My question is whether the path to becoming a "pro" camera necessarily means following in the footsteps of the DSLR. Is there something new, an as yet undefined quality that might propel m43 or some other alternate system to redefine what "pro" means? I mean 50 years ago "pro" was a Leica M2 with a 35mm lens, right? The SLR and especially the DSLR changed all that. Could it change radically again?

exactly  a well posed question, echos many of my feelings on lens s for the mount

A "pro" as in "professional" photographer is someone who makes a living out of photography, so a "pro" camera is one that a professional photographer would use, a marketing ploy to get amateurs, those who don't make enough money out of photography for it to be their main or only income, to think that their ability will improve by having the same equipment as a "Pro"
A "pro" camera could be any camera, nothing to do with price or specifications unless you are marketing cameras.

That only applies if you are selling to a "stock photography" site
If you are taking pictures of children then it is the parents that you have to satisfy with the image you are selling.

What is a "more pro" camera? A camera is a tool - its selecting the correct tool - and using it correctly that matters.

As an example if you had a blurry picture of the latest stealth helicopter used in the OBL raid you would be able to sell it easily - as there are none. it wouldn't matter what camera / lens  you used the QC wouldn't matter...it would be the ONLY picture.

"I am a current M 4/3 (Panasonic G1) user, and I shoot with Canon DSLRs as well.
My favorite Canon lens is 70-200mm f/2.8 - similar lenses exist in all DSLR families, and from Sigma and Tamron.
Of course, it's a huge / heavy lens. 200mm at f/2.8 requires more than 70mm front element diameter, and full-frame imaging circle keep rear element(s) large enough. A 4/3 equivalent would be 35-100mm f/2.8, with half of the imaging circle. Required front element will be 36mm - this lens would be not larger or heavier than Panasonic 45-200mm. Why nobody makes it?
More importantly, does this mean that Panasonic and Olympus see Micro 4/3 as exclusively consumer-grade system, so no fast zooms will be ever made?"

Thats wrong, mFT equiv. would be 52-150mm f2.1 because of smaller sensor (crop 2x against 1,5x). For me "Pro" is starting at 35mm format.

For me "Pro" is starting at 35mm format.

You know, even Medium format was once considered too small for Pro-work. Things have changed gradually since then.

There are actually several elements that typically go into the concept of "pro" with cameras, ruggedness and durability (a pro camera has to thrive in every sort of condition, and continue in this 12 hours or more a day, non-stop, shooting a thousand frames a day or more). Plus, lens need to match that. Generally, pro-level lens _do_ also have greater light-gathering capabilities, hence the lower f-stop number. Look at Canon's and Nikon's pro line lenses--f/2.8 at 400mm? This also serves to make the lenses huge and unwieldy. This requires massive bodies that can handle the heavy lenses. Also, weather-proofing cannot be forgotten.

And then, there is the way they handle. There tend to be more manual controls, and more discreet controls, rather than depending on nested menus. Oddly, knobs and wheels also tend to require greater effort to move (at least those that would wreak havoc, were they accidentally moved) Their viewfinders are larger, covering 100% of the exposed frame, and they are brighter. Generally, you have to understand photography and the camera in order to get the most out of them. They will not assist you in any way to understand what you are doing (like the art scenes modes or other simple operating modes). I think also, that the viewfinder in a pro camera will give you much more info than you will find in a consumer camera, especially one designed for beginners. A pro camera, however, tends to contain the essentials that allow them to get their job done with the minimal of fuss, while still retaining the maximum of flexibility. That's what they need.

Oddly, some of those things that appeal to pros, and which you see on pro cameras, would make them very undesirable to consumers. That, IMO, is one reason that pro cameras cost more--to keep them out of the hands of people would just complain because of missing "features". ;-)

-Jon

But the holder had to be reversed even between the two shots, I guess. Now weddings are done exclusively with FF DSLRs, APS-C and 4/3. I don't know if anyone does these in Medium format at all.

It is funny because when the rumor came up about the Olympus Micro Four Thirds pro camera, I honestly had no idea what they meant by that. I suppose a viewfinder is needed?