Sorry to break the news to you but you should budget for two pair.
I went through the change from old SGs to new SLs about half a dozen years ago, so learn from my experience.
Things have changed, and you really should experience the benefits of the short-radius carver. They are a blast to arc turns on. More turns per your skiing dollar. Nothing will increase your skills as much as arcing a bajillion turns per run. And they are great fun.
However, anyone who spent a goodly portion of their skiing time on a pair of Kästle RX National Team SG, will not likely limit themselves to the speeds at which short radius skis work well in. Sure they will feel good enough at speed (until you take the old SGs out of the garage for old-times sake and see what your missing), but you really need a long radius ski too, and let's face it, those old SGs were a little too stiff for powder, and not the best mogul ski. A short radius ski for a fast skier is an accident waiting to happen, unless that skier has another pair of skis for high speed skiing. Good short radius skis just work too well at speed on flat smooth snow; the vibration dampening is that good. However, they can given the right conditions suddenly bite into the snow and do very nasty things.
I haven't been out west lately, but I've heard good things about the Dynastar LPs and the new Kästles.
Are your boots made of the disposable plastic, or the good plastic?