I have the mighty mini tank bag. It's a small bag that holds my gloves and the small items I carry around gps,camera, sunglasses. The quality of the bag is very good. I was not disaponnated with my bag. I the cortech red for my luggage and I need a small bag to carry around.
I purchased the 25 liter seat bag at the same time as I purchased my Luggage Locker (spent the extra to get the waterproof material).
I sent the Marsee back. As much as I like their tanks bags I found the tail bag very "tippy" and the capacity no greater than the far superior (IMHO) luggage locker.
Also the Marsee retention system did not inspire confidence.