Morningstar - I did not belittle anything, so I would appreciate not putting words in my mouth. I have had my work printed at that size from a single frame from my D800, and some even a bit larger from multiple images stitched into a pano. I routinely printed my work at 24x36 from a D70s, D200, D300 and eventually a FF D700 with no lack of quality.
Truth is, no one pixel peeps a 40x60, so 122 dpi is more than adequate at the normal viewing distance of 8 ft, which really only needs 36 ppi to give a sense of sharpness.
Your comment suggests that you might not be familiar with how this works, but here is an easy to follow guide.
http://www.pointsinfocus.com/tools/minimum-resolution-calculator/FYI - at one point I owned the Olympus PenF back in the 60s. Do you know what that was?
I have shot with the Olympus OMD M5 and Pentax Lumix GX1 with the Panasonic 45-150 and the 100-300. I was pretty impressed with the optical quality of these lenses, and images that were produced with the shorter lenses as well.
My takeaway on these on M4/3 cameras is that while they are pretty amazing at what they can do given the sensor size, they in no way compare to what can be done with even a 5 yr old D700 full frame camera - they lack the low light performance, dynamic range and color depth of the big boys.
Do I sense a bit of envy intermingled with denial here? This is all in response to your original comment about trading your m4/3 for FF.
Perhaps you should not be "belittling" FF cameras, no matter how much you love your M4/3 and how well it suits you. Such a camera could never work for me for most of the work I do.
What you might consider is that as opposed to sounding like "someone who likes the latest, newest, bestest, most expensive toys" I just might be someone who has downsized from medium and large format film (Mamiya RB67 and Sinar F Pro 4x5) and find the tradeoffs ok to live with on a D800 and just not acceptable on a m4/3 camera for the landscape, wildlife and botanical fine art photography that I do.
My advice to you is to not believe everything you think, and above all, ask before you make any assumptions and launch personal attacks without any basis. That is just bad form and completely unprofessional.