ok, i found it what i was asking at start
(maybe I wasn't clear enough to understand me :/ ) - the smoothing by Editing Normals option thing...
if faces has any smoothing group it doesn't work, only without them ('clear all' to make sure) and than add "Edit Normals" modifier so we can make smooth surfaces as we want, and no "detach to element" is needed
of course the "Use MAX Normals" is needed
its more time to make the surface smooth in proper way but I think it can look better on corners, edges itc.