A SAW would be a perfect application for caseless ammunition. Think about it -
- From an open bolt, cook-off is a non-issue.
- One of the main advantages of caseless ammo is weight, which translates to more rounds the pound. Given that a SAW is used for suppressive fire, this is a big bonus.
- If desired, positively loopy rates of fire can be achieved.
- If the cook-off issue cannot be conclusively resolved (according to the folks at HKPRO, who are entirely unbiased when it comes to Heckler & Koch's R&D projects, it was), chambering a rifle in the same caliber becomes less attractive, as it would have to be open-bolt.
- If the rather small caliber (4.73x33) of the G11 was due to a technical limitation of caseless ammo, muzzle energy would be on the anemic side.
- Ammunition is more fragile - unless it's kept in 'ammo cassettes' or somesuch and sealed until loading, you'd have bits of propellant getting shaved off whenever it's handled.