I haven't yet cast the SSF but will cast that and more at the show coming to my part of the country this weekend. I am very familiar with the VPS though, formerly known as the RPL in so far as the general blank design is concerned.
I'll reserve judgement on the SSF for now, but here's what I see as the merits of the Sage VPS rods:
They are "fast", but not stiff. They are not super-fast, like the XP series, but by no means could you put them in the mid-flex or slow category. What I really like about them is the control you feel in the rod throughout the entire casting stroke. I never did understand the interest in mid-flex; you only feel the dynamics of the cast at the endpoints. I suppose it helps those who are trying to find the loadpoints but once registered the section I refer to as the "heart" of the blank has no guts and long line aerialization is out of the question. The Sage VPS on the other hand is so lively that you feel every nuance of the cast. Stiff rods tend to negate that lively energized feel of the cast as well, although for those who cast less frequently over the course of a day (from a boat for instance) or run deep heavy lines need broomstick rods and they have their place (like the old RPL-X 10wt 9ft 3pc, a big favorite for this purpose).
Guys like me typically make a lot of casts and fish long hard days, most often from shore. I rely on a rod that does the work for me, and total distance is not nearly as important as a rod that lulls me into a rhythm of many, many casts without fatigue. Stiff rods kill me, I don't enjoy fishing them like some guys do. Soft rods kill me too - I get too frustrated not having the recoil that is, as you know, the operative physical element of the forward cast.
So to summarize, the endearing aspect of the Sage VPS (formerly RPL) is that it gives the angler a light, lively, not stiff / nor soft, all-day casting tool with a deceptive recoil hidden in the heart of the blank that does the work so you don't have to.
I'll let you know what I think of Jim Murphy's new creations after the show. He certainly is busy bringing great products to us consumer types, much to his credit. He also belts out one hell of an Irish Ballard too.