Optical interface failure rates

Historically, optical interfaces have had lower reliability (MTBF) than electrical interfaces, of the same rate, due to a high burnout rate for the lasers. This has apparently changed now, and optical failure rates are lower. Do customers perceive this as true? Do you know of estimates for MTBF for lasers vs copper, for example, 1Gig ether O versus E? Assume that we're talking VSR usage; otherwise copper wouldn't be suitable. And in terms of all optical interface types, if you want roughly 10Gbps speed but are agnostic about how, what about OC192C POS interfaces versus 10Gig Ether? thanks, -david waitzman