I don't see that much of a difference. Maybe pixel peepers can tell but the 95%of the audience watching on there phones don't care. You can mimic color/film look on most camera nowadays with post manipulation software (dehancer/film-convert/Cinematch) or hire a good color grader/editor. Will it be a 100% match to a red/alexa, NO.... but it will be close.
Why not just buy a gimbal or steadicam ?
I would go S5 all the way for the ibis, Anamorphic, full frame stills, and cinema features. It's almost close to the same price, $250 difference. Color from both cameras look good to me.
The S5 looks like a winner to me, aside from video AF/micro hdmi. For my needs, I would definitely pick it over anything Sony, canon R5/R6 and Fuji xt4.