[FrankenPC]

From my corporate experience, retaining two types of developers on staff for the two different types of challenges is a good idea in general. At my current company, we have a dedicated scrumm team working on the really large projects and individual waterfall engineers cranking out special requests. We swap out engineers between the two groups so they can enjoy creating both types of work product.

The only downside to scrumm IMO is that some companies champion it like it's the only valid solution and waterfall is demonized somewhat. It seems to me the best organizational design is the one that takes into account all likely possibilities. Flexibility twists with the wind. Rigidity eventually cracks and collapses.