I have a KAC broom handle and the Tango Down VFG. I prefer the TD for a couple of reasons. It has storage space, a removable plate to install a pressure switch, is hand filling and basically delivers as advertised.
The KAC is pretty slim but still feels good. The nice thing about the KAC is that no matter how you grab the VFG, it's the same from any angle.
As far as being "rock" solid, my TD is not. The KAC is definately rock solid since I can torque it down as tight as I want. My TD has some play which is due to the locking tabs not fully returning home as detailed by other posts in the past. (This is on a SUREFIRE rail) But it mounts more solid than not- so it's good enough for me. IMHO, there's a difference between solid, not so solid & wobbly. The TD is NOT wobbly, there's just some play from side to side.
Sly