Would 15 lb be too light for baitcasters?  I like lighter line.  Normally the lowest I go is 20lb but if the 8 layers and coating restricts digging in I am wondering If I could make 15lb work????  I find I cast lighter braid further than heavier braids but the all too often backash from digging in is a pain in the rear end. 

I started out fishing 15lb braid on baitcasters and didn't have any issues with digging in (original PP).  It has to be put on correctly.  Being it was 15lb most of the reel is filled with 12lb mono backing which was on there before and then spooled with the braid.  100yrds of braid is plenty and you won't have any issues with it digging in as long as the backing/mono behind the braid is tight and the braid is spooled on tightly.  Most won't fish lighter braid due to handling issues as most wouldn't fish 4lb on a baitcaster where I grew up fishing 6lb on mine as a teen so it wasn't a big deal, 10lb was heavy mono for me.

I use only 20lb braid and have not had any issues with it , I find it handles well and is strong ....

Used suffix and spider wire and I love using power pro can't say any thing bad about it

I have had good experiences with both Suffix and Power pro. I have used both the cheaper stuff and their higher priced stuff and it all seems to work pretty well

Here's another option to consider if you want to try a braided line that sinks - Sufix Gravity2. 12-15 lb test is similar in diameter to the regular Sufix 832 at 30-40 lb. I picked some up this Fall in 12 lb and only used it a couple times but seemed to work well enough. Time will tell if it holds up as well as regular 832 over time. But if you want some sink... may be another option to consider..