My 2 bits...
As I posted, Im not a specwar super commando or Boba Fett but one good use for a VFG could be to control full auto or bursts in a CQB environment with a short barrel AR or patrol rifle. I'm sure that muzzle would bounce all over or kick like a ticked off mule with powerful loads.
More SWAT & spec ops are moving toward the larger battle rifle calibers; 6.8x40mm, .300 AAC Blackout, 7.62mmNATO, .458SOCOM.
Muzzle blast & control would be needed + the extra wt would help too.