What Type Brand of ST Glass Digital Cable?

Having corresponded with many fellow Audiogoners regarding the best digital cable approach for Transport to DAC connections, I'm interested in looking into "ST Glass" optical cables (I am currently using top of the line quality XLR digital cables).

Knowing virtually nothing about the ST Glass optical cables, can anyone tell me which brands of these cables have worked well? Is this cable technology subject to the same variances, controversies, and sonic differences that traditional wire based audio cables are? Or, does the optical nature of these cables eliminate many of the variables that affect sonics (Accept the differences in connector quality)?

Finally, I rarely see these cables advertised. Are there simply not many being used or is there a down side that I'm not aware of?

Thanks in adance.