There are various quality discs (the disc itself) available so we always get the best we can but I've never heard of even one of ours splitting. Hard to imagine what would even split. I wouldn't even worry about that happening.
For calipers, we haven't used the non-Nissin ones since we secured a supply from Nissin maybe 4 years ago now, I forget. For a whole year afterward we offered a very cheap upgrade to all past customers.
A lot of the sandcast kits being sold in the UK come with those calipers though, and the cheapest discs. (The big problem with the cheaper discs is trueness.) Then again, so do millions of Chinese scooters.