Used it already for a couple of small on-road trips and also every-day commute and can say:
+Very robust and heavy duty
-Nobody will replace a usual backpack with it for everyday, because it is quite heavy when not put in a car or on a motorcycle
+Accessible storage. Either from both sides when on the bike, or from the "top" when used as backpack. (I started using it as a sports bag as well, because I can mount it on the bike easily and stuck with it, even when traveling by car)
+Extension loops underneath the beaver tail (next to the tent pole bag) work great for strapping a fuel or drinking bladder on top. Instead of using a backpack with water, I did put it there.
+Easy to carry thanks to the backpack straps (as stated before: not as replacement when hiking, but great for carrying from / to the bike)

Potential improvements for v2.5 oder 3.0?
-Backpack straps not easily "removed" when fully loaded. I found it a bit tricky to put the straps away, when the duffle is fully packed. I would with for two smaller zippers on the left and right and a velcro-strip where the current zipper is, so the whole panel could flap down. Its still easy to get them out when loaded, but I like to put them away before strapping it to the bike.
-The strap holes in the beaver tail could be a bit bigger (especially the inner one with the male clips).
(-It would be great, if the duffle could have some system to easily attach it to the reckless 40 / 80 base plate, without extra straps as replacement for the reckles beaver tail. But I guess that point belongs to the reckless review)
-> I found both points not worthy of deducting a star. It's working fine as it is, just two things I noticed

How I use it for every day use:
I got four 25mm loops (from a competitor) that mount under the seat of my T7 and stick out a tiny bit. I also bought 4 g-hooks for ~1-2€ each to thread into each end of the backcountry chinch straps. The straps are run below the tent pole bag and thick out each hole in the beaver tail. One side is a fixed length and slack goes out the other. The slack can be easily hooked into the top molle panel, so they don't interfere while carrying the duffle. When I strap it to the bike, I simply put all hooks into the seat straps and tighten the slack (strap the buckle does stick out on the side of the beaver tail, where the holes are higher up).
Works well so far and the main reason for doing so was, that I did not want to wast so much time on short ride with running the straps through the bike and the bag every time.

Love my 40lit Back Country Duffle V2. I have removed the waterproof inner bag and replaced it with a 40lit lightweight waterproof bag, you can reduce the weight by about 2kg doing this. I dont need the robustness of the waterproof liner as I dont plan going off road. It would be nice if this could be an option when purchasing.

The Mosko bags are great. Can’t think of anything to improve them but as I use them on a bunch of big rides will try to think of any improvements needed. The givi rack I had on didn’t work with the mosko bags so I ordered and received a set of the Motortek racks. There is room for improvement on the Outback Motortek rack. Not happy with how far the right side sticks out. Would have been better if the rack was 1-2 inches closer to the bike and maybe a heat shield installed on the inboard side of the tubes.

This is where I stored my house. All things camping. Tent, sleeping pad, sleeping bag and liner, pillow, camping chair, and my Jet Boil stove. I have a large sleeping pad that won’t fit into the duffle. However, I put it and my camping chair on the outside of the duffle under the beaver tail. That arrangement gave me a backrest when I needed it. In the future, I’ll bring a more compact air mattress and move the tent to the outside. That way if the tent is wet, it won’t humidify the inside of the duffle.

I also have the tent pole bag from Mosko Moto. My tent poles are long, so they barely fit into the bag. I had the bag mounted on the outside of one of the panniers, but that proved to be inefficient when setting up and taking down the tent. I ended up stashing it between the sleeping pad and the camping chair. Now the entire camping setup could be done by just lifting the duffle off the bike.

Access to the duffle can be by either end. I did not need this feature, but if I had to set the tent up in the rain, I could have pulled the tent out from one end and left everything else inside and dry.

I used the steel core security strap to strap the duffle across the seat by going through the racks. I made a mistake of putting the buckle inside the beavertail once and it scratched up the surface of the duffle. No real damage, just a dumb mistake. Eventually, I put the security strap aside and just used one of the Backcountry cinch straps.

This duffle was waterproof; leaving everything inside dry. The size of the 30L was just long enough that I could put it crossways on the back of my seat, fitting in between the two panniers.

A great duffle bag that needs no rainproof cover. It is made with a tough outer shell that gave me no worries about dropping it on the ground to unpack the camping gear. I could also leave it outside the tent under the vestibule without worries about water, bugs, or critters getting into it.

I use the 30 L Duffle Bag with a light load as a tail bag. It is only about half full. It packs small and holds my tools, first aid kit, tow straps, tire pump and misc. items. There is plenty of room for a jacket and other items I may want to add. It will be a a great addition to my Nomad Tank Bag and saddle bags for longer trips. And will hold a lot when full. I added a 4L Molle Storage bag for smaller items.