I Have a big bucket of these sitting here waiting for my barrel. These have garnered some extremely serious attention from US LR Benchrest shooters in the states.
Matrix bullets are as good as any bullet - quality wise - you can get your hands on. They use Berger J4 Jackets and this caliber fits in an incredibly important niche... the 6.8mm diameter is perfect for creating a very high BC profile, and soing so with acceptable barrel life and recoil.
I am building a 6.8-284 to use with these pills. According to what I have been able to research, the BC of these bullets is .700 I don't care who you are... that is incredible.
Those wanting to go the 270 WSM route are all set. Lesser cartridges will likely require a bit more twist that is considered standard for 270 barrels.