The X-bolt is a great gun.
The finish of your scope is darn near a completely cosmetic feature. I choose mine based on what looks good on the gun.
For brand names, Leupold, Sightron, Zeiss, Nightforce (and others) are all excellent, and priced accordingly.
6x is too high of a minimum for an inexperienced hunter.
Please realize that your not just going to slap a $600 optic (or $6,000 for that matter) on a rifle and be able to effectively kill elk at 600 yards. Expect to burn many hundreds (thousands) of rounds and a good, long time practicing, preferably with a good, professional trainer, if you expect to be able to shoot that distance.
Still happily answering to the call-sign Peetza.
You do not HAVE a soul. You ARE a soul. You HAVE a body.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.