For general use, they are in theory thief-proof because you can take them everywhere with you. The downside is they're expensive so you HAVE to take them everywhere with you. Leave them out and they'll get stolen. For that reason I think the happiest I've been is with a dirt cheap bike in Japan. Didn't even lock it properly (just a key built into the frame) and could park it outside any old shop or restaurant for hours. Super convenient.
It has a built in lock that blocks the front spokes, an alarm and I use a $200 chain lock around the frame to fix it to something.
The only defense is storing your bike inside. And then you get karens on the owners corp whinging that you aren't allowed to take bikes inside. Who also don't give two shits when your bike gets stolen from the basement bike storage.
For my $250 deductible I basically just get a nice upgrade to the latest version / a brand new ebike for ~$200 / year.
The peace of mind alone with insurance (and a really nice lock) have fully mitigated this for me. I've been leaving my ~$2k ebike locked up all over San Francisco for ~3 years without it being stolen. (My first beater bike was a POS locked up in my apartments secure bike storage and it was stolen after I owned it for ~9 days so I figured I couldn't double down on the bad luck).
Not any more. A new generation of locks have an abrasive-filled plastic layer that aggressively wears down angle grinder discs. They aren't completely immune to angle grinders, but the better locks will take 20 minutes and multiple cutting discs to defeat.
https://www.cyclingweekly.com/group-tests/wrecked-and-rated-...
Comparing with your CyclyngWeekly link:
- the Litelock X3 goes from 5min to cut only 50% of the shackle to 23s fully cut.
- the Abus Granit Super Extreme 2500 also could only be cut to 50% in 5min, while the diamond disc finished in 29s.
- the Hiplok D1000 couldn't be fully cut in 5min with 2 metal discs, it took 52s with a diamond one.
I didn't see a single bike locked up when I visited Japan. I was told that this is because of the high conviction rate and mandatory bike registration process that they have. Was I just in especially low-crime areas? Do most Japanese cyclists lock theirs up?