In the article he concludes that it is a matter of form and how tight the springs are setup. The Saris MP1 has fixed leaf springs that provide the resistance and return to center for side-to-side motion. Because of this their rocker plate does indeed "encourage poor form." At the other end of the spectrum, another company has quite marvelously engineered a virtual pivot point that approximates the pivot axis of a bike ridden outdoors. You will pay a premium for this though.
It is really quite simple to ride with proper form on a rocker plate once proper technique is learned and you set up the "springs" (5 or 6 inch playground balls) to a loose setting. This is essentially controlled by how much or little air you put in the balls. At first you learn to control the lean with active engagement at the handlebars. In doing so, you push the right pedal down and nudge the bars to the left, so that the bike leans left and vice versa. Again, this can only be achieved if you do not over-inflate the balls but rather have just enough air to give you a return motion. The added benefits of this loose setup are that the balls will not be likely to pop or develop leaks and you will be engaging your core constantly, making the most out of your indoor cycling sessions. To illustrate how easy it can be to ride our rocker plate with proper form watch the video here where the cyclist is riding sitting up without any hands on the bars.
