At a meeting with Tracker UK a couple of months back, they have a motorcycle Tracker nearing readiness for the market. It will work on the same principle as the car/plant/HGV system. The problem for bikes has always been that the tracker unit has been too big to easily conceal on a motorcycle.
The MO of car thieves these days is not to be detered by Tracker etc. They know that the system requires the owner to contact the police, report the theft, contact Tracker with the crime reference number, Tracker then confirm with the police and then turn on the tracker itself. It transmits at max power for a period then drops down to a lower signal strength.
The thieves know they have a few hours to search for and remove the tracker unit before the signal is activated. More if the owner isn't likely to be aware of the theft for some time. I have seen some beautiful cars trashed in the effort to find the tracker before they gave up.
The problem with bikes, Bakes, is of course that there are few places to hide the unit that won't be found quickly, less on a bike like a GS.
The system that uses a mobile phone is better in that it alerts the owner if it is activated but it depends on the owner having the phone (or in some case a pager) always at hand and always within signal. The owner still has to either stop the thieves themself or try to convince someone in a police control room to despatch a patrol (providing any are available of course!).
Not sure if you are aware but most motorcycle theft is component crime fuelled by the cost of new parts. If you tried to build a Yamaha R1 from new parts, from scratch over the counter from a dealer, it would cost in excess of £30K! There is a ready market for parts because bikes can easily sustain so much damage in relatively minor collisions or offs. Add to that the fact that many owners buy a new bike on the 'drip-dry' then find that any insurance payout doesn't come close to the amount of finance etc. and you can see why the second-hand spares market for re-builds is so bouyant. (You'll often find the frames and engines of stolen bikes in track machines). Most of the above is mainly applicable to Japanese sports and sports/tourers. BMW's and particularly GS's don't figure so much in this activity. GS's mainly because they sustain relatively little damage compared to the plastic rocket types. You are more likely to become the victim of the opportunistic thief, hence the chain etc.
It is dificult not to become paranoid about theft but in my experience, if you are someone who is aware of theft potential you tend to be less likely to become a victim.
Hope this is of some use!
P.S. Re the component thing, just as an example, I know of one case where a brand new Honda was supplied by a main dealer and fitted with a tracker unit in a sting type operation. The bike went within hours and was tracked straight to another Honda main dealer where it was stripped immediately!!!