I'm still waiting on reviews and beamshots before I pull the trigger. I've been very happy with my Emisars, but some of them are less practical than others.
One problem I had with the D4S with SST-20 emitters is that when you're at lower brightness levels, there is a noticeable green tint to the light. I didn't notice this as much with the regular D4, but I would guess that the D18 will be more like the D4S than like the D4 in this regard, and since these aren't available with Cree emitters (yet), I want to make sure I'll like what I buy. I ended up selling quite a few flashlights recently because they were not exactly what I liked.
I'm also curious just how the D18 optic balances throw and flood. The D4 with its stock optic does a great job producing a floody beam with a little punch. The D4S is a throwy beam with a little flood. I would prefer a throwy beam with a brighter flood than what I get with the D4S, which seems more like a short range search light in the way that the area outside of the beam is just dark, not much spill to light up that area at all.
Finally, I want to know how useful the D18 will be in stepped mode and what kinds of runtime people get at each level. One issue I have taken with the D4 and D4S is that with the ramping UI, it's really hard to estimate runtime at the more sane middle levels. A stepped mode sequence would help this, but only if the step configuration makes sense (I don't have any experience with Andruil, so maybe the answer is already out there). I have an Acebeam headlamp with terrible mode spacing, putting almost all the configurability in the 300-4000 lumen range, which really hurts its utility as a headlamp.
I have no doubt that the D18 will quickly become too hot to hold bare-handed and that the brightness will start to ramp down from 14,000 lumens almost immediately. I'm more concerned with how it performs in the 200-2000 lumen range, and if I get one, I might do a lot of reading about runtimes and configure a mode ceiling right around the 2000 lumen level, see how it performs like that.