A properly waxed ski will out perform any climbing skin or no-wax base. There is no maybe. The perfomance difference is significant. If fish scales and climbing skins work so well how come they aren't used for racing? Even at the Middle School level you won't see any serious racer on anything but a waxable base.
Next time a sales person says wax is obsolete, ask them if they have ever actually tried it. No one that has actually used a no-wax and waxable ski side by side could ever believe such nonsense.
As a nordic instructor I am often shocked at the lack of knowledge in the retail shops. I'ts not just the young guys at Bent Gate, the same confusion exists at REI, Sports Authority, Christy's and all of the big box outlets. Every year I find it harder to find someone that even sells a waxable ski or a decent selection of kick waxes.
Fortunatly there is Boulder Nordic Sport. They are a dedicated high performance shop that caters to the nordic folks. They have an outstanding collection of waxes and lots of expert knowledge.
Last time I looked they sold a complete line of waxes from Toko, Swix, Rohde, Start and several others. They also are the very best place for getting nordic skis stone ground and tuned.