It’s been a very long time since I have been here on Permies. Thank you for bringing me back.
My first thought when reading your post was what is your purpose for this land? Second thought was how much are you working with? So I went and found your first post where you gave some info on this.
Wife recently inherited her grandparents 286 acre farm 35 miles northwest of Lubbock, Texas. The farm has been used for growing crops, mainly cotton, milo and corn. Of the 286 acres, about 100 acres is crop land, about 100 acres is in the CRP program, the rest is native pasture. The native pasture has been overgrazed and poorly managed for 70 years and is grown up in catclaw mimosa and yucca. Grasses present are prairie grasses like blue grama, buffalo grass, bluestem and western wheatgrass.
You talked about pastured pigs. Is this all you are planning or is there more livestock? Specifically cattle or sheep? As you already know your land is a perfect example of Brittle as described by Allon Savory. His Holistic Management system is what you need to be using. It is able to do most of what you want. That being said 286 acres is going to be a lot of work no matter what you do. Use your animals and get the grasses growing. Nature will take care of the infiltration.
On to your questions: my preference is to use the Subsoiler (Keyline plot) because it is less work and faster. They both have their places in different locations and environments. The others above have provided very good information.
Do you have visible surface runoff? Is there obvious erosion? I would start there with the subsoiler. A single day can make a significant difference for short term infiltration. I am not sold on the idea that the water actually “flows” to the ridge lines when using the Keyline system, but it does get the rain into the ground. And that is what you want. Ponds and swales could be used for localized water catchment and use. Such as for your livestock.
What kind of slopes do you have? 1%, 5%, 10%. How steep are they? I am on basically flat land so my use of a subsoiler is for breaking compaction layers and getting the water and roots past that first hard layer. I only have a few acres with enough slope to justify doing anything else.