I have a 30ft. 3/4" Kryptonite cable and a Titanium shrouded padlock. Completely uncutable for any average set of bolt cutters. Plasma torch yea...ok... I also have a Kevlar lined, non cuttable/slashable Bike cover with a smaller Kryponite lock that ties underneath the bike.
Since statistics show 85% of ALL bikes taken are just dumped right into the back of a pickup truck, you need to tie your bike to something solid.
This with a Scorpion or LoJack system and you shouldn't have any issues.
If you live in a big, high crime complex and have to park you bike in the open, outside, you need every layer of defense.
Take the time, spend the money and you'll never have issues