I don't want to dissuade you from taking the path of least resistance, but though I did have to replace my Knog Boomer seatpost light, the Xootr Crossrack Bag has light loops on it, and in fact, I doubled my rear light output with this system because I put two Boomer Wearables on the bag! I guess my point is that for me, the benefits of the rack system outweighed the issue of needing to rethink tail lighting, which was not difficult to figure out.
I suppose places like a courthouse or airplane might be problem for odd pieces of metal, but generally, I don't think that's much of an issue, at least not in my life. It's a one pin quick release, so really easy and fast to pop on/off. The other option would be to lift off the bag, remove the rack, and just slide it onto your lock. Another alternative would be to remove the locking pin with a bolt. Me, I don't lockup in high crime areas or high risk situations, so not an issue for me.
The Xootr is 25lbs. It also accommodates most standard mounting panniers. I have the Xootr bag, which is capacious, waterproof (er, highly water resistant), and has secure rack (pannier) mount and shoulder strap. Very convenient for me.
The Vario has it's benefits, but it's only rated to 5kg/11lbs, which is more of novelty piece than a utility piece, and at a higher price, it just didn't pass muster for my needs. Plus, I don't trust the plastic bits to durable like aluminum, especially through my cold, Michigan winter rides.