Touring Equipment

To be honest I'd never looked in to that, but they seem very up to the job the ones from revelate designs actually hold more (L) than the rack pack would anyway.

I'd thoroughly recommend bikepacking gear. For people who haven't already bought racks and panniers etc the cost won't seem so bad either.
There hasn't been a winner of either the tour divide or the iditabike events in years that wasn't using this kind of setup...and those guys can't afford to have things fail on them, so that shows both how well they work and how high quality they are.

You just have to be sensible if going down that route though and know that these are specialist products designed to be used a certain way...meaning, you can't use bikepacking saddlebags like a carradice for example where you just throw a couple of things in them because they'll flop about all over the place.
They're designed to be used with a certain amount of stuff inside them in order for them to hold their shape and be solid.

People who race with this kind of setup will have their kit lists dialed and will know exactly what is gonna be carried where, and how to pack it properly.
The seatpacks work best for clothes and sleep systems as they can be packed in tightly then compressed to make things really solid and stable.