Noel,
Seeing your GIVI click-on bag inspired me to get one for my other bike that has a plastic tank with a painted plastic cover, so magnetics won't work.
I like the GIVI bag but am concerned about its security. Not so much about someone unzipping it and removing the contents (you have that problem with any tankbag) but with someone just UN-clicking it and taking the bag and contents.
Got any ideas to prevent this other than carrying the bag ?
Arnie
Move to an area with a lower crime rate.

Arnie, I don't worry about it. My bike is rarely out of site on day rides or trips and I am often accused of having an unrealistic faith in my fellow man's honesty ( I leave the key in it when I park it most of the time during the day)
On the larger of the two bags, like you have, you can't even see the release lever, it is hidden from view under the bag, and I have always figured that most people who would give some thought to nicking it wouldn't have a clue how to release it.
If walking away from the bike, I would usually take the only thing of value in there with me anyway, my bag containing wallet, phone etc with me.
If parked with other bikes I have always assumed an "Honour among thieves" attitude will prevail.
I also believe most petty theft is opportunistic, if it doesn't just lift off, they'll find something else to pinch, like the $800 GPS sitting just above it!
Or they could just take the whole bike, it permanently has a spare key in the compartment above the choke knob and just to show what a generous bloke I am, there is also a $50 note in there. So, if they pinch the bike, the first couple of tanks of fuel are on me.
As you know, with footpath parking in Victoria, you can always park your bike somewhere very conspicuous and in full view.
On the rare occasion I feel security is an issue, I take it with me, and the GPS, but most (all) of the time I forget about the spare key and $50 being left on it, not that anyone is likely to stumble on to that little compartment with it on the side stand with the bars turned.
I also leave my car running with the A/C on in hot weather if just ducking into the shops.
Noel