Funny thing, I happen to have both the new SL20L, and a SL20X with the Malkoff. I started a thread about the SL20L. It has a gigantic, deep reflector, and really throws. The build quality feels a little less sturdy than the venerable SL20X, and the battery is a new slim NiCad that I don't like because it doesn't take advantage of the full D size battery tube (its the Ultrastinger battery with a spacer). Overall, though its pretty sweet. I'm sure it will also get knocked because the tint is on the cool side too, but the beam profile is nice, with a tight hotspot and just about the right amount of usable spill.
The Malkoff has a warmer tint. On the site it states its about 5000K, and looks pure white to me. Neither warm nor cool. Also, as Gene states, it uses an optic instead of a reflector, so there is some artifact in the beam, but nothing too distracting. It's just not a white wall hunters dream. It feels heavy, (in a good way), and very well built. I would say over all output is pretty even between the two, with maybe a slight edge to the SL20L. Sorry, I can't do beam shots right now, so I hope the descriptions help.