I think that most people that complain about Ortliebs being air tight and not the best place to store damp stuff in the sun on a hot day where mildew becomes a problem are the people that don't stop at a motel or laundromat to dry out their stuff. They are often on really long tours and do not have access to such conveniences when they are in less-developed countries. For those people and their style of touring, I say that they should use what works best for them.

I however have a different style of touring. If it is wet out for too many days in a row, I stop at a motel and dry stuff out.

When camping, virtually every day I have some damp stuff because I do a small amount of sink laundry every day and that stuff is never dry by the morning when I am packing up. But if it is not raining, I strap that to the top of my front Ortliebs. It does not dry out there, but it does not mildew either. Sometimes I wrap it up in a towel, some trips I brought a mesh bag for the purpose.

Getting into the front rollers or back rollers is not that convenient during the day when they are on the bike, so all my stuff like food for lunch or snacks, batteries for GPS, inner tubes and tire levers, anything I buy at the grocery store, etc., is stored in a handlebar bag or saddle bag or dry bag on top of the rear rack. So, I virtually am never opening up the Ortliebs during the day.

Each trip I consider taking some non-Ortlieb front panniers since I have two pair that I can use, but I always end up using the Ortliebs.

I have toured with a friend that has a complete Arkel set and he loves them. He crossed the county with them. He has his preferences and I have mine. We still get along, after all it is not like talking politics... ... ... yet.

My Ortliebs in first photo, his Arkels in second.