There's no doubt the foilfreek(I have 4.0 & 4.8) is nicer than S-1 for cruising around carving etc. Don't get me wrong, the S-1 is good. I've been using one for a few years now. It's a bit twitchy for my liking but I put up with it because riding a 3.0 sail is cool.
I nearly bought the new R4D, but found a second hand foilfreek for half the price.
R4D is a new model so it must be better though