banjopkr, fencing is a personal preference based on many factors..appearance, cost, who you are trying to impress, what you are trying to hold in/out. Everybody has their theories as to what is best.
I understand horses, cattle, sheep, goats and have done lots of fencing on several family ranches and my own.
The most important factor, by about 90%, is the stability of your corner/end posts. I've tried everything... and now use concrete culverts 5 feet indiameter and 5 feet high, 2800lbs, for corners and ends. They don't move or rot or pull out of the ground. Put in the very best ends/corners you can and sink wooden or metal pipe welded posts 4 feet inthe ground... and use 3 brace posts.
I've used lots of wooden line posts, pine treated and creasote and texas ash juniper. I've concreted them in and just tamped them in with rocks all around. My experience is that ANY wood post, except the heart wood of ash juniper, will rot..sometimes in 5 years, sometimes in 10... but you''ll be redoing those posts sooner or later.
I use electric smooth wire fencing reinforced with a strand of barb and one or two electric smooth wires for cattle.
I now use ONLY metal T posts as line posts. I've become disgusted at any other approach of mixing wood and metal posts. It doesn't work for me. Wood rots.
You buy a metal T posts and you own it forever, can reposition it easily if it gets pulled out or bent over.
Use the bucket of a front end loader to pull t posts with a chain. Press the T post into the ground with the bottom of the bucket (careful, if you hit a rock the front of the tractor will lift off the ground and slide sideways or bend the post, or both.)
My recommendation would be to focus your money on corner posts and bracing. Use T posts exclusively reinforced by the single top strand of electrical wire, as you are planning. The horses will stay away from the fence when they are trained. The no climb fence is good... a visual for the horses and smooth to avoid injury.
As you likely know, horses can get themselves injured in a totally smooth enclosure... it happens and you end up wondering how you could have prevented it... I believe you have made good decisions re your fencing plans and the fence will be as injury proof as people can make it. If a horse goes wild and runs into the fence, it just happens and all you can do is make it smooth wire and hope that injuries are minimal. The type of posts you use don't matter. It could be argued that T posts are better than wood since they give under impact.
I had an uncle who was riding a horse in a smooth no climb wire sand arena, 6' high fence with highly visible top rail of 4 inch diameter wood juniper rail. Fence posts every 5' made from juniper.
The horse "cold jawed" on him, while running in the arena under saddle, would not turn, hit the fence head on, Uncle saw a wreck was unavoidable and loosened up in the saddle and quit the horse at the fence, going over the top rail landing with bruses. Horse hit the fence head on, split it like a pair of scissors, broke its neck and died.
Your long term fencing experience may vary... good luck. You know my recommendations.... h*** for stout corners, smooth wire, electric top wire, T posts.