MD2 with the 18350 Vapcell 1600mah and M91T (even the M61N for that matter) so far have been working out great. I'll have to see how long the runtimes will be so far so good.
Not the wall of light that the Surefire Lumamax LX2 and VME head with M91B on a 16650 is. Low is much dimmer too but...