regarding the question of ABW vs ICC print in B&W I can share my humble opinion.
First of all, I think that maybe not all the printer model have the same behavior, and obviously there are differences depending on the paper used.
With a given paper, using my little R3000 (which is not a pro printer), adopting Adobe RGB (gray gamma 2.2) as working colorspace, there are some differences, as per L* linearity parameter, between printing a B&W image in ABW (neutral dark) and printing the same image with an ICC profile (provided by paper manufacturer for example).
That said, the first advantage of ABW is that, if for example in neutral-dark I get a similar non linear behavior as the ICC one (typical dark print shape) I can try a neutral-normal setting to counterbalance it, and this is not possible in native ICC without editing the image.
This gives you an option the have a better starting point for the print, but in my experience is far from perfect too
As already mentioned, other ABW advantages are the slight deeper black I have usually got (but not so much in some cases) and the probably higher archival grade due to some minimization of colored inks during the print. Again, here results may vary a lot more with a different paper choice.
What ABW it does not allow easily is the use of a linearization ICC.
A way to workaround this is the already mentioned use of QTR rgb ICC creation and a double ICC action (assign/convert) in RGB before sending the image to ABW driver.
Finally, what ABW cannot in any case allow is a gray tone neutralization (if needed for some papers, because normally in my test the neutral gray of ABW is better that the one of the ICC print on the same paper) and/or the desire to have a split-toned image (sepia shadows or whatever) without messing with the L* linearity.
Another issue could be the over-inking, but I will leave this argument out, for the moment.
In my opinion, the use of an ICC print in B&W makes sense if you need to overcome the gray neutralization and/or the spit-tone lack in ABW.
So, usually, my first choice for B&W print is ABW with a paper I have L* linearized and for which the gray tone is good enough.
If I need to print on a less neutral paper and/or want a custom split/tone I could consider to switch to an ICC B&W print, obviously using a L* linearization which includes the desired degree of neutral gray compensation (or split/tone).
There is a post regarding my approach to the L* linearization with/without tone compensation using DeviceLink profiles here:http://www.luminous-landscape.com/forum/index.php?topic=78142.0
with some details regarding the current state of my experimentation/development and including some examples of real world results.
Unlucky at the moment is not something really usable or that I can share/provide: it is a bunch of scripts and batch files used under different applications, so it should be considered a experimental work in progress with unknown timing...
Nonetheless, I hope it will be useful.
Any opinion in regard is always welcome.