Not me, I do have a ventura rack though, you can get the 35 litre and the 51 litre bags and zip them together, plenty of storage. I also have a massive RJAYs bag. Imo buy Devo's rack on the forum if you don't already have one, surely he'll do it for 50 posted
. On the 12 she unbolts and returns to 100% stock in a minute flat.
I also have the bagster spider tail pack, it has fancy mounting crap that you put under the seat, not necessary on the 12... toss it all out and just bungee it under the passenger seat. Fits my laptop and bits and pieces for the commute, and converts to a pretty comfy backpack for the walk from the parking to the office.
I am keen to know what you decide though and your thoughts on the tank bag, because I might follow suit. Had a magnetic tank bag once that somehow picked up some iron filings and scratched my tank up, since then I've sworn off magnetic tank bags. I'd probably steer clear of magnetic bags with "optional" suction caps like the ones you linked (or at least remove the magnets when you get it)