I thought the A2 is fairly unique in that the bulb is also fed regulated voltage and does a "soft start" that avoids the violent thermal shock of unregulated incandescent flashlights. Seems like I read two consequences to that: 1) Not the best light for blinking morse code 2) No warning of battery exhaustion by gradual dimming of lamp - which is a Janus of a feature.

I don't own an A2 and I might be confusing this with another flashlight... anyway, the A2 is the most interesting Surefire to me.