Something else to consider with regard to their effectiveness (which might indicate why the teams are experimenting.) :
With the disk being mounted on the outer section of the rim, braking power is tranferred more directly to the tyre. If you can imagine, a regular disk must transfer braking power from the disks outer, to its mount point at the hub then back out to the tyre via the rims spokes. Regardless of how rigid the wheel/disk combo is, some amount 'give would exist. Rim brakes can avoid this.
The offset of this is that this rigidity may actually take some feel away from the rider however this could be countered with other features such as radial masters.
Actually I had it wrong, I thought that it be less feel due to the lever being too 'snatchy'. BUT I think /your're/ right in hindsight. (and frankly, I don't much like the sight of you hind :O) ) I think the translation of tire feel would actually end up running right through your fingertips and that this would override the snatchy lever, although some adjustment on behalf of the rider may be necessary.
Prolly just easier to ride a Buell and see for one's self.