I think a subsoiler would be great to have, and I like the idea of the shear pin. Which bolt is the shear pin?
Sometimes, I'd really like to have the shank mounted just wide of the tires. The thing I'm trying to do now is make shallow ditches between fence posts so that I can bury electric fence cables under gates. So the standard subsoiler you showed, I wouldn't be able to get it in between (and in line with), the fence posts.
I've seen subsoilers with left and right shanks, but those seem like overkill for me. I was thinking of making a mount on the outside (a few inches left or right), of my box blade and being able to attach / detach a long shank. I think adding a shear pin is a good idea!