Glad to see you post here. Some comments on your observations. David Lamb and Myself were the Designers of the first release. I am not sure which release you have, as CH re-issues quite a bit.
Originality, Presentation, Fun: All in the eye of the beholder. So no right or wrong to be had.
Why the no multi-location Fire Groups for the PAVN? This is actually covered in the Designers notes. The Viet Minh indeed did take out GM 100. With their standard 3-1 numerical and 5-1 firepower ratio which General Giap steadfastly tried to garner before attacking in force. Also, having read on GM 100 extensively, they were ambushed and nickel and dimed for a couple of months before the big ambushes were struck. The very rules you skim over, "They are like the Japanese in G etc etc," are the very rules that make them more stealthy with other special considerations in the game given them, than any other Nationality that has yet come out. As they were masters of field craft, rightly so.
They had more firepower ON PAPER, than a corresponding CEFEO formation. However, again and again in even odds or close to even odds fights, with minimal to no close artillery or air support available, they came off on the worse end of firefights that were not ambush based. The CEFEO had better fire discipline and training in that regard. The casualty reports in engagement after engagement bear that out.
When such forces appear in ASL, (Think Partisans) the no multi-location fire group rule appears again and again. Again as I say, it is mentioned in the designers notes. This was our method of handling that disparity.
So the PAVN are represented as extremely stealthy, but not a good even number match for their adversaries in a fire fight. Most of their attacks were at night. This to avoid and French air support, but oddly enough in ASL, you can't form multi-location fire groups at night either. A case of art imitating life in conveying another reason why the PAVN would prefer night.
There are PAVN ambush scenarios, indeed the Nor'Easter Pack II, recently released by LFT has one, but at DBP, once the siege began, the CEFEO was forced to accept that they would be on the defensive. It was clear who the besieged and the besieger were, so opportunities for such ambushes became scarce. There is one such ambush depicted however prior to the siege actually beginning. The PAVN were masters of ambush, there just weren't that many of them after 3/14 with the fall of Beatrice. The nature of the battle largely precluded it. Attempts to supply Isabelle at the far end of the Valley were beset by ambushes. Keeping Isabelle Fed reflects this.
Much of what you had to say in the chat seemed not to have dug a bit deeper into the above. As I say, fun is purely subjective, so certainly no way to argue that point.
Thanks for doing the review at any rate, and I certainly wish you well with future ones.