I wont touch c123 lights with a 10 foot pole.
They are hard to come by in most stores and not enough availability. Common battery types only for me.
Interestingly in the past 5 years we had 2 disaster type events here locally and the only batteries left on the shelf after it was over was C cells and 9V squares. Makes you think.
Skam
I've been using c123 batteries for the past 15+ years in the military. Shelf life is outstanding and I've used them all over from South American jungles to the sunny/sandy spots in the Middle East. I've seen pictures of lithium cells rupturing, but I've never witnessed it first hand. All our COMSEC devices (except the new ones) use 123 batteries; all our radios use a larger battery composed of 123-sized cells (these are usually pumping out 20 watts for man-pack radios). For me, there's no fear of availability, especially when deployed

I still like the output and size effeciency of the 123 cells.
Now, with that said, AA and AAA lithiums are a huge leap for the majority of battery devices. I still have a ton of AAA, AA, C, D and 9V alkaline batteries stocked in the house, but for long-term storage (think of emergency strobes, flashlights in kits, GPS, etc.), the lithiums are much better at keeping them "loaded" and not worrying about them. I've had several electronic devices destroyed from a leaking alkaline cell. Regardless, current alkaline cell production is top notch, excellent life span and as long as you rotate batteries annually, you'll be okay.
It's funny you mention the C and 9V batteries left on the shelf Skammer. That has been my experience as well. I do have a C-Cell LED, but I may look at picking up a couple of C-Cell LED Mag Lights. The PAL LED's are absoutely great! They take a 9V battery, and they last forever...with a high, low and strobe function, they're a great emergency light; additionally, a little steel wool and a 9V battery is a good fire-starter. I have one of these in both my kids' and wife's kits.
That remeinds me...I need to pick up some more 9V and AAA batteries
ROCK6