As always John,
@jdonalds , very thorough and it shows years of experience. One thing I might add, is that at least with a box anchor, using chain "can" hurt, and it will defeat the way a box anchor works. That steel arm is not only the chain weight for the anchor, it is a control arm for how the anchor operates. Without that control arm, or with a chain on the control arm, the anchor can't reset if it is to be turned due to a wind shift. The control arm only moves a total of 30 degrees either side of the tow point when lifted backwards, or between the flukes. A chain, well, it can go anywhere, and wrap into the flukes and foul the anchor. It is that upward movement of the control arm backward between the flukes in a wind shift, that pivots the anchor directly over itself, lifting, and laying down on the opposite flukes, that allows it to reset within one foot of its original position. The biggest issue I have with the box anchor, is that it is advertised to only need 2 to 1 scope, and that is only true in calm conditions. It still needs more scope, depending on boat weight/windage/wind/waves, at times. I agree with Ronnie on his assessment of how to set it. Just drop it in, let the boat drift against it, stop the rode release, and if it is still moving, pay out more rode to increase the scope. One other thing John, an additional benefit of a box anchor, one you pointed out as a negative, is actually a positive in loose sand. That is the box design. That box, as you mentioned, in firm bottom, only lets the flukes dig in the length of the fluke before the box itself is against the bottom, and the flukes are only approximately 5 inches long...but there are 4 of them! That said, in loose sand, that box squirms and moves as the boat swings on the anchor line and buries the box itself into the sand, which magnifies the hold power exponentially. It is indeed a great sand anchor. Loose sand, that is...like you said, there are bottoms that can play games with any anchor. Firm sand, such as sand/clay (sandy loam) mixes are loose enough that more scope helps, but tight enough that only the flukes dig and the box itself never fills with the tighter bottom condition.
@Ronnie , I would consider a different style anchor than the baby box as a stern anchor. It, like its bigger brothers is a great anchor, but it works just like them. So as a stern anchor, it is really outside of its operational design in terms of how a boat will pull on a stern anchor. That pull is going to be lateral more than directly against, and I think maybe it won't be as effective as other anchors might be. I could be wrong on this, but the beauty of a box is the ability to hold in varied conditions with opposite load, and to only be unearthed by shifting winds within the margins listed above. The problem with a stern anchor, is the load is not opposite, it is on the primary anchor as opposite, and the stern anchor is more lateral. Now that said, using an anchor buddy on the primary does put a load on both anchors, so I may be all wet on my considerations. But just wanted to throw it out there in case you hadn't considered it.
While it seems these discussions are more opinion laden and less factual, there is plenty of science in this, but there is also art! I love that you bring that up. Because setting a fluke anchor takes both, setting a richter or a box is less difficult, more often successful with less effort, and not as subject to wind changes uprooting them permanently.
. I have a roll of reflective tape that I use every 10' so I can count scope. I have the roll of it, but I haven't put it into my rode yet 
. I run it out until it feels right. Each of my rode is double fisherman's knot tied to each other at 100' increments. If i am 30' I usually run out 90' of line (just before the first knot) on my LBA. Take my Manson Supreme and I'm running out 200' of rode (of course I only do this if I expect 60mph winds).
