To start I can already see that fighting words are likely to occur, here so some rules before the knives start to fly:
NE conditions (sorry don't ski the west enough to have a fair outlook, though if anyone has extra skis, plane tickets etc for powder skiing for at least a month, I can be persuaded to change the thread....you know field testing and such...nudge, nudge, wink, wink).
During this past season I have lent my GS FIS ski to some individuals who thought they were pretty good (and so did I). But I have quickly learned (and so did they) that a GS ski while able to do railway tracks on just about everything does have one other characteristic that often forgotten until you find it.
It is responsive, to every input or lack there of. Make a mistake it bites you. Lose focus it bites you. Forget to give it direction rolling into a turn it bites you. Let your thoughts wander about food, it bites you. This is the ski that will praise you if skied well with performance and hold like nothing else in the world, and instantly punish you if skied it wrong.
In that regard, I would suggest that a GS ski is likely the best ski to prove and prefect your merit as a skier. Once you have perfected the GS ski anything else is easier as you still carry the fear of the bite and won't make those silly mistakes.
So my vote goes to the GS FIS ski, perfect it and all else just falls in place.
Have at it (nicely and with fun).