I am an armchair physicist, and I was struck by some of the statement's on the DW-LINK page, notably:
Originally Posted by gastro
Newton's Third law of Motion states that "Every action has an equal and opposite reaction." When a bicycle accelerates forward, the rider's mass is transferred rearward. Without something to counteract this mass transfer, the rear suspension on most bicycles will compress under acceleration. This mass transfer as a reaction to acceleration is what riders have come to know as "bob."
First of all, if your mass [or more accurately, center of mass] shifted rearward when you accelerated, your position would have to change relative to the handlebars, seat and BB. Since I don't slide off the back of my bike when I start pedalling, I'm thinking that's an inaccurate statement. What actually happens when you push on the pedals is that a torque [torque = moment x distance; see this link for a better description] is applied to the rear wheel that causes it to want to rotate. If the wheel were glued to the ground, you would pop the front end of the bike up in the air, assuming that the torque around the axle were large enough [i.e. a wheelie]. A moment applied by the chain to the rear wheel overcomes the torque produced by the force of gravity acting on the center of mass of the bike and rider.
Still with me? Good. So a moment acts close to the center of the rear hub, and as long as the resulting torque isn't so big that it lifts the front of the bike up, and you don't break traction, you will move forward. You're riding! There is no transfer/shifting of mass unless you move your butt off the seat or let go of the handlebars. This is not "bob". Bob comes from sloppy pedalling. That's right - it's your fault. Think of a dirt bike. Many have single-pivot swingarm suspensions, but they don't bob, even when subjected to massive smooth accelerations. If you give the throttle little twists as you ride, the seat will droop with every little application of torque to the rear wheel. You bounce, because there is a giant hinge in the middle of your bike - it's designed to bend at that point. Thus, "bob" is a result of the inconsistent torque produced from inconsistent pedalling motion combined with the pivot in the middle of your bike. It's exacerbated by not using clipless pedals.
Squat is similar. Just about any rear-wheel drive vehicle has squat to a certain degree. The torque acting at the rear wheel[s] wants to send the front wheel[s] upward, but as it does, the center of mass rotates about the rear axis and more force is applied to the back of the bike/car/motorcycle. Assuming you don't flip over backwards, the suspension will usually compress and you squat. How do you fight squat and bob? Use a Horst Link, or slap on a pro-pedal shock or run enough spring rate in the rear shock that it won't compress. The stable-platform shocks are tuned so that small forces don't compress the shock. This typically means that they don't react well to very small features, like small stones and roots, but it all depends on how the shock is set up. Of course, on any sizable bump or rut - plush travel is the order of the day. Without these shocks, VPP and non-Horst four-bar designs would bob and squat like crazy.
Like I said, I'm just an armchair physicist, so don't take my word for it. If all this really matters to you, and you ride with clipless pedals, just go and ride some bikes with different designs. If you can turn the pro-pedal feature down/off, see what kind of a difference it makes to the "bob" and "squat". Odds are, the non-Horst bikes will bob.