This is my take which generally reflects what has been said by most in this thread with a few other thoughts.
Detuning with a pocket stone lightly at the tips and tails may be fine in certain conditions but I would not ask the shop to do any "detuning" unless you find out exactly what it is they propose to do. If your skis feel "hooky" when you ski you can have the shop increase the base edge bevel at the tips rather than having the tips dulled back. Check also to see that the tail bar evenly meets the ski edges.
With conventional skis that were longer with straighter sidecuts, shops would often dull the tips and tails with a file presuming that they were intended only to be used to skid turns. The result was that that then became all that the ski could do. This was okay when skidded turns were the norm for most skiers.
Now skis are designed to carve much more easily than before. Aggressive "detuning" of shaped skis defeats the purpose of the designers and limits the possibilities of the skier.
What I would do first is to check that the bases are flat along their length particularly at the tip. With wider shaped skis they are often very concave out of the box(with really wide tips it may not be possible to get them completely flat without removing a lot of edge). New skis can be concave, convex or both at different points along their lengths. If they are not flat ask the shop to deal with that issue.
Check each ski for warpage which you can do by placing the base of the ski against something very flat like a plate glass window. Apply a little pressure against the ski and check to see whether it lies perfectly flat against the window at all four contact points or if it rocks back and forth. Warpage can occur in skis and if it exists then have the shop replace them because warpage cannot be corrected.
Although some skiers may have personal preferences when it comes to base and side bevels you should be safe if you stick to the ski factory specs when asking the shop to do any work on your skis. The designers took base and side bevel issues into account when they designed the ski.
Flat bases, with no warpage and a factory spec side and base bevel generally seems to reflect the attitude of ski shop techs that I've talked to for most skis sold today(I understand that Atomics have their own considerations which have been the subject of some interesting exchanges in past threads but since you bought Salomon's there is no need to get into that discussion here).
A final thought, I don't know whether the CrossMax comes with pre mounted bindings or even exactly how their system works. When mounting conventional bindings, the bindings should match up with arrows on your boots and the arrows or centerline mark on each ski unless you have a special reason for mounting them forward or aft. I had an experience once with one binding mounted properly and the other one way off. I only discovered it when I went skiing.
Have fun with your new skis.
Unfortunatly I've taken an oath not to by new ski equipment this year. I wonder
If a new ski jacket counts.