I have to admit that after using the RP for a while the focus peaking really does work much better than on older mirrorless cameras. I don't know if this is because it's FF, or just improved tech, but it works to such an extent that I could use my collection of old, mint Takumar M42 lenses in a 'live' situation. Using the exposure simulation mode in the viewfinder I can shoot at what aperture I like, using the aperture ring on the lens, without the problems of a dark viewfinder, and benefit from real DOF and overcome any issues with lenses that have focus shift. In fact with these mirrorless FF cameras there's not much point to the manual lenses that couple to the camera electronically, and are much more expensive. However, having said that I see that quality old 35mm lenses like many of the Takumars are going up in price rapidly. Maybe this is why.
I have to admit...one of the MAIN things I've found to enjoy about mirrorless interchangeable cameras is........adapting and using old vintage lenses on them.
My vision is crap...but with the focusing aids, I find I really don't have much a problem. Heck, as I'd mentioned on another reply...I'll often preset my cameras sunny 16...and prefocus the lens based on that and just walk around snapping away when something catches my eye.
I LOVE my modern high tech lenses....for when I want them.
I'm really growing more and more, however, to appreciate the imperfections and character that old lenses can impart and they are really inspiring me to try new things. And for the most part, those lenses can be had a VERY reasonable prices.
Hell, it's really making me excited many weekends to go out and hit garage sales...its amazing what old lenses (and film camera bodies) you can find for almost nothing and they are in good shape.
Last year, I scored a mint condition Yashica MAT 124 G medium format TLR camera....I offered $75 and walked out with it. I likely could have gotten out for less, but WTF, you know?
But now, I'm on the prowl for lenses.....you just never know what you'll find.
And there's pretty much any adapter for any lens to any mirrorless camera mount out there that you'd want.