Hi, it all depend what you are planning to do with the skis. If you're planning to do park (and only park) the middle (of the ski) will be perfect as the Salomon TNT is dedicated to park but you will struggle in the powder... if you can, because the noze of the ski will dive. The more you'll go back the better it would be in the powder. If you're planning to stay on the slop, the best is probably the middle point (which is not the middle of the ski) and you keep the polyvalence of the ski. 

It actually depends if it's the only pair of skis you have.