First of all, the proof is in the pudding.
There are very few, if any IH 7 on the Shore, or Turners. I wonder why. Lack of strength, serviceablility and high cost relative to needs probably have something to do with it. There are a lot of SC VPP designs here, so I will belabour this point. I will not go into bikes that are a non factor where I ride. Remember, my point of view is relative.
Turner and Ellsworth designs are excellent for pedalling and braking, but the design itself is inherently linear rate. The Dare (I owned 2) and the Rogue (my friend is selling his after 3 rides) both had the same problem. They both could be real plush but bottom out, or not bottom out and be firm. The Fly does both. Platform shocks do not help; the Rogue has the Fox DHX 5 on it and still the same problem. So the 4 bar link works, but time has caught up with it. If you are more cross country, jump right in. Not good for what I need.
VPP must be in the sweet spot to work properly, and this is determined on springrate and rider weight. If not set up properly you will either close the shock with each pedal stroke or pull the rear end towards the BB with each pedalstroke. Either way, not good. You do not feel it much, but compared to a 4 bar design, you will notice it. The SC are not of the same manufacture calibre as Foes, no comparison. The one problem SC has here is the pivots are very maintainence costly. Weather, torsion and wear all cause the bearings to need extra attention compared to other designs. My Dares only needed a change once every 2 years, the Foes, I changed them every year anyway but my buddy has not changed his since new, 3 years. This adds up and if one is not mechanically inclined, will frustrate them. I have seen people sell bikes for less cause.
Frankly, what you own is irrelevant to me. You chose what you own based on what you like, and this is relative to where you ride and what. The environment I subject my bike to is the most demanding possible, for terrain or weather. And between myself and my friend, we have owned 1 Kona, I Rocky HT, I Mountain Cycle Shockwave, I Intense Uzzi DH, 4 Dares, 2 Flys and I Ellsworth Rogue. This does not count the frames we have tried and rejected and each frame was an evolution on the one previous. Each got better. I have never ridden a 5 Spot, nor will I. Turner is hardly represented here on the Shore and warranty support is non existent. Ellsworths have fallen out of favour with all the Joker breakages. Foes has good support. SC is popular due to being cheap, as quality frames go, but you see NO Intense VPP. Intense has never had a strong showing, and I can go into why, but not here. But the fact you don't see them tells you something.
Riding locals will determine, in the minds of the locals, what is good or not, but this itself is somewhat biased. I rider in the Dakotas that calls a bike good may find the bike not so good as the demands of the trails goes up in harder riding locals. To my view, as a lifelong Shore rider, the bike that is good should be strong, reactive, ramp up and be pedalled. Braking should offer no ill effects. There is no perfect bike, but from the list of needs and wants, the Fly right now, represents perfection. Come ride with me on the Shore for a year in the rain and snow, and see what I mean. If you think that the fact I ride on the Shore exclusively adds no creedence to my words then you are mistaken. All bike design, currently, is based on Shore needs. Gussets, bigger headset insertion, larger bars, raked front ends.... all of this stemmed from bikes needing to be stronger to survive the cutting edge, which so happened to be my back yard. It didn't just happen, it evolved.
The principles of the VPP design have been clearly laid out in articles and magazines, and anyone paying good dollar should do the research. I love bikes, and will pay anything to get what I want and what I think is good. If the VPP design were for me, I would of bought it. When the V10 came out people bought it but found it heavy, hard to maneouver and thus they are not nearly as popular. I find it shocking you do not know the working principles of your own bike. To not know how the s curve design works and how chain pressure affects it only affirms to me that PT Barnum was right. Not to say you were duped, but to buy something not fully aware of every facet proves to me most do not know much about the bikes they own, technology wise. I cannot fathom how you can ask me to prove that VPP needs chain pressure when it is the very principle of the patent (location of the transition in the S movement). I suggest you look in a magazine that has a Specialized add that is many pages long. It goes through every design and explains it in one paragraph. Of course it is a little slanted, but you will be educated.
Like I said, come ride with me for a year. When you are changing bearings in 3 months, don't ask me to help.
Most Specialized Demo bikes are the same. DU bushings wear real fast and the pivots are hard to get at and time consuming. Matters to me, as I do all my own work.
But hey, each to their own. I enjoy my rides, hope you enjoy yours.