I have no vested interest in touting the Microdrive (other than my own positive experience), but here's something to keep in mind.
There is no reason to believe that a solid state drive is going to be more reliable than one based on a hard disk. I once heard a good argument from an engineer who pointed out that solder joints and other mechanical components are in fact more likely to give way due to temperature variations. vibration and impact than will an HD. I don't know if for a fact, but based on people I talk with and e-mails that I receive my guess is that both types fail at roughly the same rate, which is — extreemly rarely without misuse.