I had a 4810 and the gamma you are getting was my experience as well (avg around 1.5 u shaped)
Using Calman with i1pro, bat cave, 110" 16x9
Also undersaturated green (Typical with JVC it seems) unless I used the animation mode If I remember correctly (It was one of the mode not typically recomended like film, natural etc)
I played around with the JVC controls for ever and could not get a decent result, that is getting gamma correct left a dim picture. I could never understand how people were running the iris
at really low numbers like -12,13,14 and have decent brightness. I had to run mine way up to get reasonable brightness.
I have a radiance mini with 125 point autocal via calman software.
Using the mini with JVC animation mode and running auto cal I was able to get pretty good results. Much better than with the JVC controls.
Nice flat gamma, very good greyscale and 125 point color with very low errors.
I was somewhat satisfied but the pic was still bit dim, little lifeless in some scenes.
Now I came from a Epson 5020 and upgraded to the JVC since it was said that the JVC would be "brighter" in best modes than the Epson, not to mention better blacks, eshift etc.
Well just not my experience. The Epson calibrated via the radiance in natural mode was much brighter with similar results in auto cal (Flat gamma 2.2, grayscale, 125point color).
My eye told me this, but also the meter showed around 14 lumens with the epson vs 11 with the JVC both after the autocal. Both were slightly higher lumens prior to cal.
I know the i1pro is not an accurate lumens device but since I am using same meter for both it is relative.
Now I liked the JVC picture better, better pixel fill with Eshift, better blacks?? maybe hard to say without side by side compare and little more "film like" image but I always felt like I was missing something with the dim pic.
Maybe I got a bad sample? I returned it and went back to the Epson for now. Not knocking JVC just did not deliver in my case.
Waiting for real 4k and better brightness before my next upgrade, be it JVC or whoever can deliver those.