What type of lights do you use? (detachable?) and why?
- Detachable is good for theft security and for swapping between bikes (why own two lights when you can just buy a spare mount?)

Where do you use them for? (to see or be seen?)
- Both, depending on the situation. Multiple modes help with this - flash or solid.
- Newer more powerful models (compact too) are making this easier.
- Tail lights need a bit of side on visibility

What do you expect in terms of lifetime?
- Depends on the initial cost outlay. Top end lights I'd expect many years (3-4+) from the light itself and maybe 2-3 from the battery if rechargeable.

Maybe some other stuff that's on your mind?
- I'm moving to rechargeable lights (USB - convenient, less waste)