One thing I'd like to add about the Hound Dog XPG is that it does have a fair amount of short range spill which is pretty nice out to about 50 yards or so, and then the center of the beam continues to travel out to about 250 yards. So it can be fairly useful in short range situations as a general purpose light, but the hot spot is pretty bright.
Also, all of the Hound Dogs and Wildcats have the Hi/Lo level selector by a slight twist of the head, so you have 2 useful brightness selections. The "Lo" is more like a "Medium" and is somewhere around 50 lumens, which I find sufficient for basic flashlight use and that saves battery life too. The Hi/Lo function allows you to select brightness level before turning the light on, or after it is on, if that has any importance to you.
The bodies are all compatible with the 18mm type rechargeables, such as 18350 or 18500, or 18650, so they are all set for the high-capacity rechargeables. The MD2 could take a pair of 18350, and the MD3 could take a pair of 18500, and the MD4 can take a pair of 18650.
The tailcap is Surefire P compatible, so it can take most aftermarket tail caps for Surefire, and the Moddoo Triad fits it.
MD2, MD3, MD4, all come with a McClicky switch already, so it has the best switch available as OEM.
The reflector is a custom McGizmo reflector, and Don makes the best reflectors, so that's why Gene had Don design it.
This stuff is the best, IMO.
For the money you pay, it's a steal.