I've been playing a fortress with this mod lately, and I've really been enjoying it. The extra challenge of making steel has been fun and had made me a better DF player...I really had to master the job manager for this fort! I panicked at first because I couldn't find any bees, but I was able to start making wax locally with bayberries. I also think the combat is indeed much better balanced.
I also had a great time playing around with all the armor types. I've got all my units kitted out in masterwork steel: padded coif/full helm/circlet, padded armor/cuirass/mail cape/paudrons, belt/mail skirt/lower plate/tassets, full arm defense/arm plate, and greaves. I like to picture them like bipedal tanks.
But, I have had a couple of issues. The reward for making steel has been soured by the tremendous amount of steel being dumped on my battlefield by the local goblin tribes. I nearly always get two goblin invasions at the same time, who kill each other before they even bother to attack my fort. I saw someone else mention this issue in this thread. I checked, and they are not at war in my game. But the balance problem they present is that they leave massive piles of steel armor and weapons lying around every time.
I've played this fort for 17 years. Every bar of steel I made locally, I made with a manager job, so I can count them easily in my game log. 306. Meanwhile, I have 6117 bars of steel after making more armor and weapons than I'll ever need. Plus, I drastically slowed my melting in the last decade or so since the bar stockpile was overflowing. I have no idea how much steel I have in total, but I have over 100 of each kind of crude steel armor waiting to melt. I might have more then 10000 bars of steel, so I've managed to produce less than 3% of the steel that I own. So if there is a way to get the other civs to stop bringing so much steel to sieges, that would have made the few steel I managed to produce a lot more meaningful and precious.
Another problem is that the humans that joined my fort are a bit...odd. The strangest thing is that quite a few of them are extremely old, like over 110 years. I let a few of them join my fort but I get tired of them dying of old age shortly afterwards. But, all of them, even the centenarians, are ridiculously good fighters. With the bonuses they get to training military skills, they blow all my dwarf units out of the water. Plus, most of them started with legendary skill in various military skills when they emigrated. So, that's taken a bit of fun out of training my squads, because it feels like such a slog compared to training up a squad of humans. It seems like you were trying to give the humans a buff to add challenge, but now with the update where we can have human soldiers ourselves, it's having the opposite of its intended effect.
One last niggle is that it seems weird that it takes fuel to boil bayberries into wax. None of the other "cooking" reactions like making drinks at a still require fuel, so this seemed unintuitive.