Just recently, I was looking at some of the stronger locks available out there and there was a thread on here which came up with some heavy-duty tackle if one wants to make one's bike really secure.
It's probably worth mentioning that the real tough locks and chains are intended for motor cycle security rather than the bicycle-based machines we choose to ride. The weight of the best stuff is a hindrance on a bicycle. For that reason, most cyclists choose from the "compromise" range in the bike shops, ie, not the cheapest and not the most expensive. If you look around places like Cambridge with loads of bikes chained up or shackle locked against railings, etc, the typical kit used would never deter a serious bike thief but it might well stop thrill-seeking kids.
There's a judgement to be made and a balance to be struck in bike security and different solutions will suit different circumstances, geographical location not being the least important criterion. If you're going to the trouble, (and cost) of insuring your bike, provided you can demonstrate that you took reasonable steps to secure the bike, (receipt for decent lock/chain/cable) you should be ok if you have it stolen. If, on the other hand, you are determined that no-one can ever remove your bike, the cost and weight of the equipment you'd need to carry around will be considerable.
I have middle-of-the-road security on my bikes and that suffices for me but others will describe kit that they feel comfortable with in their sphere of activity.
The final decision will be yours Penny.
Regards,
Indalo