The Steiner 415 and Ventrac 3000 are smaller, almost home owner units. If your not doing huge amounts of mowing they would work fine. The larger model, 430 has a 27HP Kohler. We sell that for $9800.
The steiner and Ventrac are simular machines, as you've heard the designers are the same. Ventrac has a few pockets where they seem to sell okay, Steiner has a much broader base of dealers. Resale value for used steiners is insane. They are built so well they really hold their value. If you compare them side by side the Ventrac is usually more expensive because the design is more complex. They use more rigging to get the controls to the side of the operator instead of the front. Visibility is also worse. I am a Stiener dealer, so I am biased... I am sure a ventrac dealer would know the flaws of my machine too.