I've not tested the breakaway strength but having worn it around the house and garden and not suffered any detachments it seems ok.
I did worry about loss and so a security chain is clipped on when out and about.
Only problem was in tapping the titanium, it's tough stuff so I took things nice and steady.
It's quite convenient in use as you just pop your keys off, sort the lock and then they clip back together really smoothly.
Similar thing on a gadget website set me thinking about the idea.
Plasma