Another full stick run!!
Put one more tick on the "you can cut full stick" side. I'll say it till I'm blue You Can Cut Full Stick, I Cut Full Stick Every Week
I've been cutting with SZs for the last 12 years and no you can't do it on every property, with every grass type but IMO I have some of the tougher grass types to cut. Can't be too rough, too steep, too thick, or too wet but when the conditions are right these machines save cut fast with a good cut. If your one to argue it you need to spend some time on a SZ. But be careful you may buy one.
I also think the weight debate is off base. When your talking crazy weight like tanks,yahts in rough waters, and the like, there is so much weight it starts to effect the surface it's riding on too the point the surface starts taking up movement or motion. A six wheel drive army truck weighs more than a Honda Civic but the Civic will ride better. IMO most of it comes down to absorption, weather that is the surface it's running on, tires, FF, springs and shocks, etc. You can make a Semi and a 15 pound mountain bike ride well given the right absorption.
Wheel base length on the other hand IMO is a factor as a long with how the machine is balanced. Hang the engine too far out the back and the front gets light but you'll be able to nose down a hill better.
I still think the distance between his ruts, rear tire psi, and possibly his deck springs are the root of his problem. The seat of my pants tells me my Kendas on the rear of my 460 ride worse than the Carlisles on my SZ at the same psi. My XR7 deck is so bloody heavy my wife can barley lift it and that's with 2" of adjustment at the front adjustment rods instead of the 1" they recommend.
Brian O can you verify if the springs on a vx4 are beefier providing more lift than earlier versions?