I have a roadid from the link given. It was about the same price including shipping as getting one in the UK (can't remember the addresses for those - something like'ice id'). Plus, it came in purple, whereas the UK ones I found didn't! Yes, this was a very important factor
I do have ID on me - when commuting, my driving licence is in my wallet which is in my handbag which is in my pannier. However, I like having the ID round my wrist - first responders generally look at the wrist or neck for a medic alert or similar thing, so they would find my ID pretty early on. It has my name, DOB, and phone numbers for home, husband and mother.
Besides, if I were in some sort of incident where I was incapable of telling them who I was, who knows where my pannier/bike/etc would end up. And, they're not going to take the time to go rooting through my things until later on.
So as I see it, having the ID on my person rather than in my luggage means my husband will get the bad news that much quicker
Having said all that, I'll happily admit to being an anxious person (I have a diagnosis to prove it and everything

) - so I'm generally a little more paranoid about these things than most people.