I have it on my boat as part of the insurance requirement, I also put it on my tender RIB engine and plotter, it costs me a damn more than that per year, possibly charge what they can for different uses although you get a small bottle of the stuff and loads of labels so I have marked my home door with a sticker and put it on computers and bikes, I very much doubt the police would scan every item looking for the stuff, if you put it in a discreet place they possibly wouldn't find it anyway, you can see the milky liquid mark after its applied.
So in answer I would say the stickers are a deterrent but the chance of getting your stuff back almost nil.
Be careful as once you sign up they will constantly take the direct debit out, you have to give a clear 30 days cancellation so when they remind you they took next years money out last week it's too late to cancel!! Maybe use it for a year, get and use all the stickers then cancel in good time for the following year. The stuff will still be on your bike so if the police do find it and you are no longer a member I have no idea what they would do.
Hope that helps.