I was also thinking that one of the reasons I would prefer rebar is
bacause at least that way, you know what you are getting. With the
fiber you probably can't tell by looking at it (can you?).

Oh yes, you can see it if you re there. Picture a bunch of inch long chopped
fiberglass tufts. You can see them sticking out while the crete is being
poured and also after its floated..they still stick out but to a lesser
degree. I saw one recently where they poured a hot tub slab, I said I
wouldnt want all those tufts sticking out of my slab (it was a broom
finish). I was told they wear or break off later and disappear...maybe they
do

R