There are some interesting mechanics in Peter Berry's rules. On the other hand, there are some clunky ones. Trying to use them is a bit like buying a classic 1967 Triumph motorcyle, v. one made in the last couple of years [a completely modern bike].
How much time do you want to spend tuning and fixing these rules?
What is your "reality quotient" in the sense of how much "real feel" are you looking for? Some people like to emphasize clever game mechanics that make for a great game. I think the SAGA system is a great example of this. It is a fun and engaging GAME, but it is also, well, a bit "gamey".
so despite having a few of PB's rules, every time I've intently read them in preparation to give them a go, I find myself tuning and fixing them up, and then I give up.
The retreat v. hits mechanic is pretty interesting. One can certainly argue that falling back is a way to reduce stress, or "hits" and it can make sense. On the other hand, it can be abused so that someone who gives a lot of ground take few casualties.
I do like the game's level of play, one that is rarely seen in gaming, whereby a unit is a company. It makes for a good level of fighting in North America.
I hope that is helpful – I could have easily posted the same question!