Stable vs edge builds is a good point. There's certainly a need for the edge builds i.e. testers, getting new features immediately etc, but it's also important to highlight and encourage using the stable release for those certainly on release builds. If you're on snapshot, chances are you are more likely to be aware of this.
The wiki could basically present two paths stable and edge and go from there, I'd imagine OpenWrt devs would encourage the use of opkg and as you've said that could be classed as the stable installation and then edge builds could be using your original guidance/script. I'm not sure if the opkg package will ever ship an edge build, it is more likely to probably move between the stable versions even in master.