Found another article quoting an ARDEC engineer:
Re heat / cook-offs:
The rotating-chamber design provides better heat management. Combined with the insulating properties of the plastic ammo cases the LSAT LMG has potential to decrease the possibility of a cook-off or eliminate them altogether
Re accuracy / lethality:
The cased telescoped ammo still provides the same muzzle velocity, range and accuracy as the brass-cased ammo. We’re not sacrificing lethality for weight. The plastic case does the same job.
Another significant feature is the long-stroke, soft-recoil design, which provides a noticeable reduction in felt recoil over the current SAW. This significantly increases control, thus providing the shooter the ability to put more rounds on target and making the weapon much easier to fire from the standing position as a result of decreased muzzle rise.
Also, according to never-knowingly-accurate Wikipedia:
- the caseless version of the gun has been in test since 2008
- the caseless weapon is 1% heavier than the cased as it requires additional seals in the breach
- pricing is expected to be equivalent to the current SAW
- they're also considering other 'more lethal' (read: larger) calibres (makes sense)
So all good. Unfortunately, no-one's expecting either of these to be adopted any time soon ..