Great review!  It seems you think the bivy sack excels in certain applications, but is not as versatile as others.  Is this paraphrased correctly?  

I think that sums it up pretty well, for example you would not want to rely on the Alpini Bivy in a downpour of rain as it is not 100% water proof. We tested the top fabric in a rain simulation and it beaded but ultimately water got through and the sleeping bad ended up getting wet, the bottom of the bivy is water proof though. As well, you would likely not want to go on a month long adventure with this being your retreat each night (you would not want to do that with any bivy sack though) as it does not have a pole to keep the hood off of your face and can feel restrictive to those not used to bivy sacks. 

The Alpini bivy does excel at being a very compact and light weight bivy for use on summit bids, emergency situations and alpine specific trips. I am not sure any one bivy sack would work in every situation - I guess that is the same reason we have multiple skis in the quiver?