In getting ready to ride my TTSE to a conference in Maryland... from Colorado... I was debating on getting Triumph brand inner bags. I needed something for the good clothing of the conference and something that would be easy for all the other stuff needed for the 3,700 mile trip. By luck or accident I stumbled upon the Osprey Transporter 40. IT FITS IN THE TOP BOX LIKE IT WAS DESIGNED FOR THIS PURPOSE, ONLY!!! At $70 from the local hiking outfitter store, it was very reasonable. With 40 liters of space I was able to take all I needed for the conference short of shoes. The panniers were used for bike gear, shoes, lite coat, and two days of travel clothing. The bag handles can double as backpack straps... very helpful since I had to park the bike a mile from the conference.
In addition, I got the Osprey Straightjacket 32L compression bags for the panniers. They are 32 liters and are square-ish. I would imagine that they don't fit as perfectly as the Triumph inner bags, but the compression straps helped me to compress clothing and items so that they would fit. I used two on a side... one behind the provided elastic straps and the second in the "door" behind an elastic strap I made.
Being versatile and nice looking, I will be using them for other trips when the bike is not involved.
I am not an Osprey sales person, but I did like the light weight and cool construction of the Osprey rev 1.5 hydration pack. The mouthpiece is at a 30% angle so it is easy to use under a full-face helmet on those 100 degree days across the mid-west United States.