I purchased a Signature II Lite Ruby several months ago and it's the first and only knife that I've carried on my keychain. While I thought that I'd be using the red LED light more often than the pen, the pen has helped in a jam or two.
Once, I was stuck in line at the electronics department at Wally World, behind a guy needing to sign a traveler's check and the W*W "associate" didn't have access to any writing implements. So, out came my car keys, with my Signature II Lite, and I opened the file, popped-up the pen, and handed it over. It probably saved me ten minutes of time and aggravation.
GeoThorn