the s7's are by no means stiff in any way. and considering the fact that he is looking at the super 7's means he wants a stiffer than not ski. i have flexed and compared the jj's, s7's, and super 7's side by side and they are pretty damn similar besides the narrower tail on the rossis. the only bad thing about the s7's is that they are pretty crappy to ride switch on.. i may be wrong but i dont think that is what OP is looking for. not everyone on NS is a park rat who wants to try dub corks into powder when it storms.
i worked at a shop and i have experience with many different skis.. personally i have EP Pros and i fuckin love them, granted they serve a totally different purpose..