Not necessarily so. I certainly was a URT/Sweetspot skeptic, but after speaking with John Castellano over a couple of years I was convinced at least to throw a leg over a Sweetspot and give it a go. I'm glad I did! Up until riding one I couldn't quite wrap my brain around how you could stand up and crank and not be fully locked out, but (without getting into it here) you can.
My Breezer Twister is one of the plushest, no pogo XC FS bikes I've had the pleasure of riding. Trust me, I'm eating a lot of crow writing this because I've talked a lot of sh*t over the years about how URTs in general are a retarded design, and some others may be, but the Sweetspot design does work and nicely for XC applications. You certainly wouldn't want to freeride a Sweetspot, but it was intended as a XC specific design in the first place.
Not only is the Zorro a clean implementation, but very flexible as well in regard to it's wheel sizing, etc.