I've tried both the flat base and the hollow base in 9mm and in 38 Spl and I like the HB better. I did notice a bit tighter groups too. I just got 500 of the thick plate only because that is all that Dillons had on the shelf when I was there, but I don't plan on driving them any faster than the regular ones but they do cost a couple bucks more.

BTW does anyone know if you now use full jacketed load data for the Thick Plate or does one stay with the reduced mid-range? Seems to me if they are rated for higher velocity then you would need more powder to achieve it, putting you into the upper end of regular jacketed load ranges.