Well, on the topic of suitable sewing machines. Ideally you would want to be in the mid-range of your machine's capability, so when we sew all our goofy shit, there is a nice reserve for when you decide to sew that really thick build-up. To WTF's point, for production sewing of all this stuff, something like the Consew 206 series really rocks out. So if you're trying to make a buck at this, that is a machine to consider. Where I would beg to differ with him, would be for the knucklehead DIY guys like us, who tear apart and modify all our shit, just cuz. This is where the 8700 series really shines. Regardless of what class machine and what it was really intended to do, this kind of machine has proven to work well for many stitch bitches over the years. Taking as a starting point that you can damn-near use any sewing machine to make this stuff (and there are a shit-load of guys that have posted their stuff online to prove this), where you have plastic home sewing machines on one end, and walking foot industrials on the other, I think the 8700 series strikes a really good balance between capability, ease of sewing, and maybe price.
So if you are a young, entrepreneur, what WTF is saying certainly makes a lot of sense; it is conventional wisdom that most guys in the biz are using what he recommends. But if you're like me and just can't find that right pouch, so you're gonna do it yourself, I think the 8700 is money. That is why I tell most guys who ask to get one of these things. It's much easier to learn on, can do about 90-95% of what the bigger machines do, and can actually sew in some tighter spaces (especially with a "zipper" foot) than a walking foot. So for repairs, modifications, one-off stuff, it rocks out. But for production runs, not so much.
I used machines very similar to it (the old Mitsubushi 130 series) in a paraloft setting for many years. You have to make lots of repairs to canopies and containers (and some times harnesses) which require getting into tight spaces, sewing "vertically", and being able to join anything from parachute nylon to cordura and webbing. If I was using "E" thread (No. 69) I was usually on a machine of this type. We only used walking foots like a Consew for "3-Cord" thread, and a "Class 7" Singer 7-33 for "5-cord" harness work. I only point this out because all the materials and techniques (not to mention machines) are directly transferrable to tactical nylon work. So if it's a "one-off" piece, this machine handles it very well.
On the other hand, when I worked at Bianchi/Gregory, here you would do a production run of say 10K gun belts. So you would have maybe 10 different machines set up for sub-assemblies, with each machine tuned to whatever was being made underneath it. This is what I think WTF is really referring to, when he says the walking foot is the way to go. And it is, when you're doing production batch work like this. You would get a tub of say 50, and work your way through it; one particular sewing lay up, all week! The walking foot is king for this.
This is in contrast to the way I usually sew, which is one guy, one machine, one complete item at a time. This is a complete waste of time for a real production facility! And I found out the hard way, being good at custom sewing for your buddies is light years away from what they do there. So I thank the whole crew there for putting up with me as long as they did.
Bottom line here I see apples n oranges being discussed, where what a very professional OEM sew shop recommends is not necessarily what the solo stitch bitch would recommend. Two different worlds really; lots of overlap, but radically different ways of operating.