I've used CSB-1 for about 3k rounds thus far in 9mm and like the powder. I am now testing some CSB-1M. It has smaller flakes and is (I believe) slightly faster than CSB-1. The CSB-1M is similar to -1 in that it meters well, has low smoke, and is relatively clean. The density is higher so it doesn't fill the case quite as much as CSB-1. It is as accurate as CSB-1 in my tests with 124 Bayou TC and 125 SNS RN bullets. Here is some data:
Glock 19, 75deg, sunny, mixed cases, CCI SPP, Bayou 124 TC @ 1.085", Pro Chrono @ 10', 10-shot strings. These are "production" loads out of my Dillon 650. I did not weigh each charge.
4.4g Avg 1108, ES 30, SD 10
4.4g Avg 1101, ES 29, SD 9
4.3g Avg 1087, ES 27, SD 9
4.3g Avg 1090, ES 22, SD 7
4.3g Avg 1086, ES 27, SD 7