Nice article as usual.
A few comments/observations:
1) I disagree with your comment on stacking, I don't think it's strange at all.
We can agree that we have to have some mechanic that prevents shielding multiple units while stacking. You suggested (in essence) randomly choosing a unit but that also (in essence) shields all the remaining units thus not doing anything to prevent a 'stack of doom'.
Your second suggestion would be some beneficial modifier for additional units. That is, the first person gets attacked normally but the rest get some kind of cover benefit. I would counter though that you still aren't taking into account the unit density. If you cram a whole platoon of infantry into a hex, you are likely to be able to cause more damage with a single bullet than less arguing that you should actually have a penalty for stacking multiple units.
Secondly, and this is for those who are going to say hey, that doesn't work on armor!, having so many units together also makes it easier to hit. So more bullets (or rounds) will be able to hit as well for the same or less effort. So I think the current rule is a pretty good compromise considering all these factors.
2) You mentioned under the technical section that there were several minor bugs but you really only mentioned one (the save game bug) in the review. I think it would be beneficial to list what you felt were bugs so that if people refer back to it, they can see if it bothers them or if it has already been addressed in a patch.
3) I understand how visually you may think the flank bonus may not seem very helpful but it might be helpful to think about it in a different way. Take a situation where you have a LMG (Atk 4) attacking a Soviet Rifle from the front (Def 12). In one die roll, you would need an 8 or more to hit which you would get 41.7% of the time. If now you attack from the flank (Def 11), you would need a 7 or more. This you can achieve 58.3% which is a full 40% better odds (58.3/41.7-1)than from attacking from the front!
I think that's a pretty significant impact. While your odds are still low if you use a Rifle to attack (Atk 2) (odds are 16.7%), your improvement from attacking the flank is even greater. In fact, it increases your chances by 2/3rds to 27.8%. This is using an example where the difference between front and flank is 1 but the benefit increases exponentially as the difference between front and flank modifiers increase. In this way you can also see how small +1 modifiers (such as hasty defense) really are helpful!
4) Finally I would offer the tip that if you like to use models, you should turn on the unit names with the 'n' key. It makes the models much easier to follow, especially in terrain. There are already suggestions, such as adding unit bases or rings to help be able to follow them easier but this tip is a good thing to do until then. Who knows, you might even in the long run prefer it to unit bases.