Yeah, you have, on average, about 2min of straight run-time on the white light. After that, you have just enough juice to run the laser(s) for a time. It's a problem.

The -16A is the go-to for A4/M4 within the GCE, with the -15 to be mounted onto crew-serves. I don't feel that the loss of how streamlined the -15 is on a personal weapon is worth a crappy white light and the added bulk of the -16A. And both the laser and light nodes are easily knocked off when banged against a HMMWV door at the wrong angle.

Better a -15 and a lo-pro light; better ergonomics, better light-life, less clunky, you can set it up so you don't need any @#$%& tape switches.

There is, however, an effort being made to replace the incandescent in the -16A with an LED head, to make for less power draw and better durability. Many of the -16As have had the bulbs pop under extended periods of fire, though that's more of an M4A1 thing.