I've got them both, an A9s (Special Edition Q5) I bought about 2 months ago, and a DBS/2SM(Q5) I got just last week.
I also have the optional 2SD pill for the DBS but am using the 2SM right now in order to compare the two lights using CR123 batteries.
After playing around with both of them and comparing them side by side in all respects, here's my personal thoughts, but remember, YMMV:
1. The Tiablo is definitely better machined and finished than the DBS, but I have no complaints with the DBS either. It's just that all the machining and finishing on the Tiablo is "cleaner" and "sharper".
My Tiablo is the natural finish, simply because I prefer it over the black.
A friend of mine came over the other night and I wanted to show him one of my new lights, and it's the Tiablo I showed him just because it's so darn pretty.
2. I have SM reflectors in both of them, and I actually like the A9s beam better. The DBS beam is ringy while the A9s beam is a nice, even white center transitioning out to the spill.
For my part, I think I'll leave the SM reflector in the A9s and let it be my "thrower", and put the OP reflector in the DBS as more of an all-purpose light.
As far as pure "throw", yes, the DBS has a deeper reflector so it will focus a tighter beam, but I'm not that happy with the pencil thin beam even if it reaches as far as it does (plus as I said earlier, the DBS beam is ringy). I prefer the wider smooth beam of the A9s (with SM) for throw because it still reaches out, but it does so with a more useful, wider beam.
3. I don't get the comment about someone liking the DBS better because it's heavier (which it is) and larger (which it is).
While I can see stuffing the A9s in my pocket on the way out the door, the DBS just crosses the line into being a "holster" light.
I am much more impressed with the fact that the A9s is really quite equal to the DBS as a thrower light, yet, does so in a smaller package.
4. I do prefer the forward clicky on the DBS for sure. Also, with the DBS, I like to be able to turn it on to the last brightness setting without having to click through other settings to get there as with the A9s. Not a big minus for the A9s, but still, I like the "saved setting" design of the DBS better whether with the 2SM or 2SD module (which also saves settings).
5. As far as runtimes, I can't say because I haven't run any batteries down yet in either of them.
Lastly, I can say that I like them both a lot and wouldn't trade one for the other. They're both keepers in my collection, and I know I'll be using both of them more as time goes on. I'm anxious to get some 18650's I have on order because the primary use of the DBS is intended (by me) to be used with the 2SD module and rechargeable battery while having the 2SM module on hand for when the power goes out and I want to use CR123's as backup.
I have always only intended to use CR123's in the Tiablo so that's why I bought the A9s model instead of the A8.
I will add that I am a little disappointed in the build quality of the DBS compared to the A9s considering that they cost within just $2.00 of each other. Still, if I lost the DBS tomorrow, I would order another to replace it.
I currently have the new "improved" MRV-SE/Epsilon on order which is now supposed to put out 265 lumens, and my primary mission for it is to get the extension tube for use with 2x18650 batteries which should give some hellacious runtimes.
For all three of the above lights, I have (or have ordered) both the SM and OP reflectors so I'm sure I'll have some fun playing back and forth with how their beams change with them.
That's my totally unsolicited .02 lumens, and I'm sticking to 'em.