Your army boots sound like a vast improvement to what I used. Mine had woefully soft uppers; no support at all in the heel area. It was an attempt to stop sore foot injuries (blisters, pump hump etc). They were responsible for a lot of soft tissue injuries (torn ligaments and tendons - sprains and strains). And to make it worse, the army supplied dubbin for those boots - that made them even softer. The leather would stretch to eventually leave you with loose boots; in the interim they didn't give much support. I still have black parade boots of that era - much tougher. Unfortunately they covered the leather with shiny black stuff that doesn't breathe - this keeps the water out but locks perspiration in. The pic below is what I had, although a tan colour.Actually I only remembered later that the terra combat boots I mentioned were also made by redback . its not a conspicuous fact on the boots .
I wondered if the soles went through different phases , trial and error in the time being made , as I have noticed slight hardness differences in a couple pairs .
There is at least a couple different tread patterns .
The boot leather consists of kangaroo hide snd buffalo which I do like the leather, and the seatbelt looking strap sewed to the sides . The first time you realize they make no attempt to stop water coming in is also pretty wild , it just gets out quick too, theres little drain holes with mesh on them looks like they can be plugged?
On a hot north queensland day the outside leather can change back to being completely dry walking through grasses in around a half hour sometimes.
There would be more expensive better lasting boots out there for sure . They did not seem to get it spot on , and I don’t think anyone would write home to say how great they are .
They do grip and they do support .
About those zips , never had trouble with one ,knock on wood . Whatever the great big zips they are using are , they should go ahead and use them on a lot of other items out there .