Try to get good answers for these questions (i.e. take mine as a starting point but wait for others to reply). As far as I know, there's no good way to use a monolift attachment alone. Once you unrack the bar, the monolift arms move out of the way and you have no way to rerack the bar. So unless you are going to set it down on the pins, every time, I'm not sure how you would make use of it. I'd love to learn something new here, though.
Stick with the pipe safety system. Straps are hard to setup and have been known to fail. If you bail on a lift (as opposed to just fail gracefully and set it down onto the safeties), if the weight is heavy enough, you will damage the barbell even with straps. I don't know numbers for this. I'm guessing about 600lbs on the pin/pipe safety vs 800lbs onto the straps. Is your rack rated for that much weight?
The reason the barbell gets damaged if you completely bail is that it is falling quickly and the pipes/straps have very small contact area with the barbell (the pipes' contact area is infinitesimal if both are perfect spheres and don't deform which they will). However, it won't hurt the barbell to be places onto the pipes and then to rest there while you unload it.
There are some much better squatters than me who have dumped bars inside of power racks and damaged them. I guess I'm not at that level yet. Most I've failed is in the 300 range and I was able to control the bar and set it onto the pins. Maybe there's a scenario I haven't encountered yet.