A rider in my group used an MSR 6L dromedary bag for gasoline for the first time about a week ago. I could smell gas whenever we stopped so I pulled it out of his backpack to check. No fuel leaks (no wet spots) but it sure did smell. The rider that was carrying it already has the biggest (the only) tank available for his TE250, but at 2.9gallons we knew he would need to carry much more for our 300 mile loop with only 1 fuel stop. The MSR bag did the trick but it will only be used on rare occasions. My concern is that if I can smell it, there is vapor in the air and fuel vapors are obviously very flammable. I have tried to convince him to buy a Nomad tank http://www.nomadtanks.com.au/Tanks.php for the rear of his bike, but we don't have many loops that have great expanses between fuel stops to justify it. For the cost of the MSR bag it was worth trying and I would still recommend using it, just try to strap it to your bike outside of any bags/boxes.