I brewed my first 10 Gal batch yesterday and I have to say - What was I waiting for?! It takes the same time as 5 gallons - so if you are planning / building your AG system I definitely suggest planning to be able to do 10 gals. For me, the time it takes to brew a batch is the most precious resource. When I brew beers with OG 1.065 or less I will probably do 10 gallons from now on.