I have both 5N and 7 with EVF and CV lenses, and alhough I do not use the CV lenses on the 7, I do concur with your finding, the placement of the EVF at the left side makes it more difficult to use your left hand.
The 5N is more natural to operate, as you can not only use both hands more effectively in manual mode, but you can also tilt the EVF for an easier viewing position.
Having said all that, the CV lenses are easily adjustable with one finger, and sliding it across the focus point, whether in focus peaking mode or in zoom assist magnification mode is rather easy and well controlled. Also, the camera/lens combo is very light, it is easy to hold.
Focus peaking works well for smaller apertures, I would rely on zoom assist for wider apertures.
The EVF does help with MF because a) it has a higher resolution which shows the effect of focus peaking a bit more subdued, as opposed to the LCD which shows a lot more peaking and b) its higher resolution helps in seeing more of the detail than the LCD which does help, and of course it is easier to see in bright daylight.
I own (and enjoy) a NEX-5N, but had an opportunity to use my manual focus CV lenses on a friend's NEX-7. I really enjoyed the camera but had some trouble getting used to the ergonomics of using the left side viewfinder and manually adjusting the focus and aperture on my lenses. I was thinking of getting a NEX-6 (because it is better suited for my 15 and 21 CV lenses), but now I'm not so sure. The ergonomics with a viewfinder on the 5N seem to make more sense to me.
Do others similar observations? Do you just live with it? Do you adjust?
Jon
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Cheers,
Henry