Would you bother with the 12mm F2, 17mm f1.8 or 45mm f1.8 if you had the 12-40 f2.8 Pro?

I'll reiterate what I said earlier, would you bother with a lens that weighs the same as some full frame lenses on a system inherently designed for system size/weight advantage. Inherently my answer is no.

Every time I walk into my local brick and mortar store there is a sales representative that tries to sell me the pro lenses, my resounding answer is the same answer every time. "Yeah, no, buddy, not interested." A couple things:

• I use F/1.7-F/1.8 for light advantage. F/1.8 gives me the same aperture control as F/3.6 http://howmuchblur.com/#compare-2x-17mm-f1.8-and-1x-35mm-f3.6-on-a-0.9m-wide-subject. I don't want to start an equivalence debate it is what it is. It's already a pretty wide aperture so I can use it wide open, and it's equivalent to about 1 to 1.5stops of light advantage over F/5.6.
• I may have to reframe my shot a bit but F/3.6 is a completely usable aperture to shoot everything and all of the prime lenses I own work well wide open whether that's the 12/2, 20/1.7 or 45/1.8. The real world advantage is 1/60th of a second vs, 1/20th of a second hand held, with one you can stop motion with the other you can't at base ISO in less than average light.
• I use it for noise advantage, you need this for four thirds sensors also. Again you get a full stop to 1.5stops advantage. If you go the other way that's the difference between ISO400 and ISO800 in less than average light, or alternatively ISO3200 vs ISO6400 in really challenging situations.
• I use it for size advantage, sorry to reiterate but are you serious or kidding me? By the time you load up an E-M1 with a 12-40 let alone the 40-150 you're in the same weight/size territory as a Sony A7, and then what point is there to be shooting with a system that loses its footprint?
• I want to get close to the stage in a situation where I would be otherwise wrestling with people in a mosh pit environment with a long lens, I whip out my 20mm lens and get the shot.
• Some venues only allow lenses of certain sizes, the longer lenses from Micro Four Thirds especially the pro lenses may fall afoul of this.
• Finally, subject isolation, if all you ever want in the world is F/5.6 that's your choice also, sometimes people want less than F/4.

That about sumarises things right now, I really do like these kinds of threads out of a matter of bemusement simply because I don't agree with them, but that's about as much as I can say at the moment without offending anyone in particular so I'll leave it at that. I have a fairly sound reason why I won't be buying any of the pro lenses, you don't have to agree with me and that's your prerogative also.