The Proflex was awful. MBR did a vintage full squidge test a year or so back and were appalled. My own experience would agree.
Ed, I'd like to.think you're right. I guess the thinking is that the tiny loss of pedalling efficiency would be offset by the system keeping the wheel on the road better. But, and its a big but, just because a.prestigious.company has come up with the idea doesn't make it any good, or even neutral in terms of its effect. In the cycling pantheon alone we have the likes of Biopace, low normal mechs, and Headshocks to remind us of this.