I've had mixed results using the middle buster for trenching. Last weekend I had 40 feet to trench to install 4"
drain pipe. Ground is sandy gumbo and was too wet to be worked. (I should have waited. Trench was 1/2 full of water when I was done.) The mb tends to push dirt ahead of it, instead of up and out of trench as I expected. I had ten feet of perfect trench, about 12 inches wide by 12 inches deep which took several passes to accomplish. The remainder was filled with the dirt pushed in from before it. After several passes to clear out, the soft wet soil was giving way and I had two deeper trenches from my tires on either side of my intended trench. I finally gave up and used the fel to finish. To quote another poster, "I stink."
Last summer I used middle buster in a field for 1/2" irrigation pipe. Opposite situation: dry sandy soil. I dug a good trench but it tended to backfill with the soil which had the consistency of talcum powder about 6" deep. I was able to lay pipe on this and just step on to push down under powder. It worked.
I plan on making a narrower blade, 3-4 inches wide and try it, but haven't yet. I've seen some good posts here with pictures for cable/pipe layers so they may help you. I feel like I'm doing something wrong and figure I just need more experience. Renting a trencher is of course the best way, but I'm too cheap.
You'd think by now the tractor manufacturers would have wised up and start selling a 3 point trencher. I've never seen one though.
Good luck.