It depends on the lens, and on how careful I am when focusing.Do you experience problems with misfocusing?
The E-M10 has focus peaking, which makes manual lens focusing much easier -- this video purports to tell you how to set that up:
You think the GX7 is better than the EM10 for manual focus? As it's the thing I'll mostly do.I have used rangefinder lenses on my u4/3 bodies quite a bit. My favorites being the Voigtländer ltm 50/1.5 Nokton and 75/2.5 Color Heliar. I also use my collection of Nikon F mount lenses. My favorite body to use with adapted lenses is the GX7. The excellent focus peaking enables precise manual focus.
I also tend to mostly use focus assist. I have my record button set for it. I also have Fn1 set for peak focusing, but I don't use it near as often.I don't bother with focus peaking (E-M5) as I found it is not anymore effective than just using 7x-10x 'normal' focus assist tool (the zoomy window thingy). I link the focus assist tool to the top button for quick access.
I have not used the EM10 so I have no comparison. My eyesight is not what it used to be so I use focus peaking quite a bit. I find it to be well implemented on the GX7 (and GH4 that I tried out). In my experience the GX7 is wonderful with adapted lenses. It is very close to the 35mm rangefinder cameras I used to shoot. It is very traditional feeling with the focus and aperture rings on the adapted lens and the shutter speed controlled with the top (called the front dial by Panasonic) knob. The best advice I can give is to try manual focus on several cameras and choose the one that works best for you.You think the GX7 is better than the EM10 for manual focus? As it's the thing I'll mostly do.
Will get some 17 or 25 mm later on for autofocus... But not necessary just yet.