In most cases it isn't an option, you use what the hardware uses. I can't decide to use an SFP+ in a unit with XFP form factor. I select the hardware according to the features I need and then buy the optics it requires, I don't select the hardware based on the optics modules it uses. The only drawback I have seen so far is finding ER optics in SFP+ form factor but they might be available now (I couldn't find them a year or so ago).
George, Good point. Perhaps the context should be more nebulous? Given a choice in an ideal word, not limited by the selection of hardware manufactures, which do you prefer? ras did a good talk on optics in the past, I'm sure there's some points to discuss.
A good topic might be ipv6 migration strategies: dual stack or native v6 with nat64/dns64
Alright, added. Are you volunteering to speak to one point or the other? Thanks, Tom