WK93, what caliber do you want to shoot? Ballistically speaking you need to determine how far you may shoot an animal, that will then narrow your calibers down. The 7mm Rem Mag will have plenty of "knock down" on any lower 48 game we can hunt as long as the bullet you shoot has a high ballistic coefficient. The high B/C bullets will maintain their speed better creating more kinetic energy and will also be substantially better considering the environmental factors that effect the bullet.
The 300 RUM is also a very good cartridge since you mentioned that one with a lot of bullets to choose from.
As far as Christenson Arms go, they will guarantee the accuracy of their rifles, but they will determine which bullet. They will build your rifle, run several different loads through it and pick the one that meets their accuracy demands at 100 yards. So you may not get the best bullet, but the best bullet for grouping at 100 yards on paper. They will put any bullet in the gun you order but wont guarantee the performance.
I personally think the 7mm is one of the best all around hunting cartridges for the lower 48 and it probably doesn't get enough credit.
Lastly, all else being equal a 6 pound gun wont perform as well as a 9 pound gun. So going light doesn't always mean your rifle will be a shooter. I would rather have a couple extra pounds with me and know if I shoot something is dying.