I've generally had good luck with helical inserts, over multiple brands and materials. I think one thing that helps is I use a tiny bit of oil on the insert before it goes into the installation tool, then wind out a about two turns of the insert before bearing down on the actual part.
The exposed insert gives me an easier time centering on the tapped hole, then observing how the first few winds perform. If everything looks/feels good, I just wind down to the stop.
The extra stickout also allows me to check that the tiny drive pawl on the install tool is properly nestled into the bend of the insert tang. I think this area may be a problem for some insertions, if the tool isn't oriented correctly it can displace or break the drive tang prematurely.
Another (more expensive) option is to use the tangless inserts, which saves breaking off the little buggers but requires much more expensive insertion tools. But they are a lot easier to remove if you have an issue, using the (expensive) removal tool. I used a bunch of 2-56 tangless back when they were pretty new on some aerospace parts and was happy with the results.
