So may be a dumb answer, but I haven't seen too much of this being an issue in most of the server chassis and backplanes I have used. You have to remember storage companies like Compellent (even now under the Dell brand) are using a Supermicro chassis. If vibration was that much of an issue, at that level of customer you are building your own chassis. Then again, I get really close to my back-of-the-napkin estimates in terms of performance so I have not bothered to look at this.