I have just tested the milkIt Booster head with a slightly dented 3 year old 750ml €5 Quechua (Decathlon) Sigg-style bottle and I was not killed by flying shards of metal. Your mileage may vary.
I carry this bottle on most big rides so thought that the head may prove a useful addition to my backpack, for the sake of 20g. To be fair I’ve only ever seen one friend need to reseat a tyre on the trail but he did manage it with CO2. Will I ever use it on the trail? Probably not, but see “for the sake of 20g” above, and I could say the same thing about a few other things I carry too, plus I fancied it for home and roadtrip use anyway.
I emailed milkIt directly a couple of weeks ago asking if a decent mini pump would inflate the bottle OK on the trail and they replied no problem, but better to use their smaller bottle (600ml) if using a mini pump in order to reach a high enough pressure a bit easier (85-120psi). I replied to thank them and that I planned to use my existing Sigg-style bottle with the head and received no further reply from them.
I ordered the head from Bike24 after that. It arrived leaky but was replaced immediately by Bike24 after I sent a video demonstrating the problem.
The replacement head arrived today. I connected it to the aforementioned bottle and inflated it with a cheap track pump while a heavy towel was wrapped around the bottle & head in case of explosion. When I hit about 140psi the head popped off the bottle just a little at a slight angle with a long slow hiss. I then unscrewed and reinstalled the head no problem, inflated again to 140psi and it held fine, and tested the inflation on a tube. The bottom of the bottle is now very slightly bulged outwards but it still stands up on a table OK.
milkIt’s own instructions say to inflate to 160psi. 140psi was getting pretty tough going for my track pump so that’s as high as I would have gone anyway. I’ll it for real at about 100-120psi when I change tyres in the next few weeks but am not scared of going to 140-160psi if need be.