I use both, depending on the bow but mostly a slightly rounded belly for osage. I'm working on an ALB now that has an almost flat belly but it fit the style of bow I wanted to make. An osage bend through the handle recurve I made last year had a pretty flat belly and I made an ELB with a deep rounded belly and that worked well.
Osage can handle practically whatever you throw at it and shine.
Hey Dano. Where ya been?