The 15 spoke Superturismo Evolutions fit our cars as they are 17x7 +48. There are at least a couple of us running these rims on their RS's, myself included.
IIRC the 16 spoke Superturismo Corsas have a +45 offset and less so there might be some fender rubbing there even if the bolt pattern matches up... I don't know if it does. Mind you the +45 offset doesn't stop the Mim rim proponents any less.
I find it really odd that the Scoobyworld site has a pic of a ST Corsa which IMO is not compatible with our cars.
If you are looking for the OZ tarmac wheel as seen on the older WRC car, those are the Superturismo Evolution and were designed specifically for the Impreza and have one less spoke. Last I heard they were discontinued.
I will check with my contacts overseas and see if they can get any (if any are still available).
A little while ago, I was happy to find pretty good looking replicas of the 17" 16-spoke version, weighing 23 pounds (like the original) and costing approx $250 each (a fraction of original). I don't know if she still has them. Contact "Sugar", via the i-club, she is a highly respected and established vender.