cheezweezl
Veteran
FF35 can get shallow as a few inches and you are not going to be able to pick it up and run with it. It will take time for you to learn how to pull focus on that format (even S35 isn't a walk in the park).
it can get even worse than that. for example, shooting a cu on an 85mm wide open, your DOF is paper thin. like less than an inch. you really have to be on your sh*t to keep your actor in focus. forget setting marks. your actor will never nail it within an inch so you'll need to wing it. a hi-res monitor (and a bit of luck) is your only hope.
i have recently started shooting on the ex1 which has really strong peaking and in whatever color you want. i set mine to red and crank it all the way up. it has really made the difference. there is no doubt about whether you are sharp or not. whatever is in focus just pops out bright red.
to be honest though, as you said, it's really not much easier on S35 like RED. slightly deeper DOF but still a challenge shooting close subjects with long lenses...