For me first one is more interesting, because there is visible more details. But I think you used to high value of "DE step factor". Standard value is 1.0 but for higher quality you should try value around 0.5. Then ray-matching will be more accurate.
"No DE shading mode" didn't use distance estimation for calculating normal vectors (necessary for calculation angle of incidence of the light). It "analyse" fractal shape around calculated pixel by calculating pseudo gradient (of binary potential function) using around 200 points. It is very slow but works very good also when calculation of distance estimation is impossible or not accurate.
Yes, i used 1.0 DE step factor.
i'm trying with lower value. Thx for the tips, i'll upload the result
