No to "knock off gear"....I would have no problems buying from them if you know what you are getting (e.g. exact model).
I've picked up my Volkl Kendo's at Sport Chek when they were blowing out their gear (e.g. they DO NOT like to hold inventory) and they are EXACTLY the same ski as the one in the ski shop.
My friend actually bought his V-Werks Katana's at Sport Chek at the end of last season because they were such a great deal. $550 CAD compared to the $1100 CAD the ski shop was still asking for the same ski.
A bunch of race parents loaded up on Hestra mitts for the kids at the end of last year too.
I picked up all our Sidas Pro boot heaters at Sport Chek as well given they were literally $120 less per set than what the ski shop was able to do (even factoring racer pricing).
So yes Sport Chek is perfectly safe to buy high end gear, they fully back warranty as well (I had a boot heater battery go wonky and they simply swapped them out for new ones).
You will notice that their high end gear selection is MUCH less than before (I believe their buyer didn't bring as much in for good reason).
Service and knowledge is hit or miss (mostly miss) but on occasion you'll get a race coach or somebody that actually knows what they are talking about.