I agree that it’s definitely worth buying a high quality lock. It’s not something you should economise on. But, for most of us, the likes of the Hiplock D1000 will be way over the top. These locks usually cost around £250, and they weight around 2 kg.
Still, if you’ve paid a four-figure amount for a top-of-the-range bike, I suppose the cost can be justified.
I also agree having your bike registered. A friend of mine recently had her bike stolen. But the police managed to recover it and trace back to her via the Bike Register scheme.