I also use 20 lb. Sufix 832 on my baitcasters for every application except topwaters especially "walk the dog" baits. After experimenting with topwaters using braid on my baitcasters last year the baits got tangled up too much, and I never could get the baits walking quite right. I switched back to 14 lb. Berkley Trilene Sensation this year.
As far as the heavier braid, I still set my drag as I would when using a lighter line. Since braid has little to no stretch, unless that smallie is able to pull out some line when making a hard run it's much more likely the hook is going to pull out. In the end, the fight is the same.
I agree with Scott and Jonn. I've never had any problems with the braid "spooking" the fish when fishing the DuPage and the Kish despite the clearer water. I even use 10 lb. Sufix 832 (Lo Vis Moss Green) with no leader on my spinning outfits when finesse fishing small plastics and landed plenty of fish in the 17"-19" range last year.
I too used lighter lines in the past worried about visibility, etc. At least for river smallies, it doesn't seem to make a difference. My guess is river smallies only have seconds (sometimes fractions of a second) to decide whether or not to strike before the current carries potential prey away from them. Not to mention the river current is constantly carrying bits of this and that downstream. Even if the fish can see the line it isn't going to think that it's any different than the other harmless bits of stuff that are constantly floating downstream.