RE: Sabots
The 12 ga NEF and H&Rs seem to not like the faster light loadings. Some have good luck with them, but most are reporting poor accuracy with loads that are faster than 1700-1800 fps and bullets lighter than 400 grns.
I have an H&R ultra slug gun and it likes the winchester Platinums pretty well, others have good luck with remingtons. Mine didn't like lightfields but others have said they shoot well.
Really you just need to try some different brands and loads to see what works well in your particular gun, they can be sort of picky. It can get expensive though. I still haven't tried all the ones I want to. I'm going to try the hastings rounds this year and see how they work, among others.
Paul