I finally got the Bags Connection Engage tank bag in. I see other members have the bag as well (Search the forum for Engage). It's a nice bag although a bit pricey - I paided $168 for the bag plus $20 something for the attachment rings and then with shipping handling and whatever else it was over $200.
It's a solid bag and with stiff sides and doesn't slouch over the tank. The gas tank connection is very nice and solid - no magnets or straps to fiddle with. And you can connect a camera mount to the SW-Motech gas tank cap attachment if you so desire.
The bag itself has several seperate compartments and pockets for organization. I didn't buy the XL size and just got the regular Engage bag and I find that holds enough for what I plan to put in there. My manuals, papers, small electronics, tools, etc.
It took me about a 1/2 hour to install the whole system. That included the SW-Motech gas tank connection and mounting the bracket to the bag. The bracket for the bag is not pre-installed and you have to drill the holes yourself. That was a bit of a downer - you pay 168 dollars for a bag and you have to drill holes into it.
Once everything was installed and setup - the bag connected to the gas tank perfectly. The test ride proved the concept works and hold the tank bag in place very nicely. I like that I can add accessories to this bag like a GPS holder and it can even be electrified! But, the $85 for that option could be best spent elsewhere.
Finally, the bag doesn't contact the tank at all - but that doesn't detract from the looks of the bag and helps to protect your tank.
Pictures of my Bags Connection Tank Bag