I highly doubt that if a 5 man powered Hsien HMG were allowed it would replace the dreaded Kamau sniper as the yardstick against wich all other shooting units are currently measured.
I beg to differ. The Kamau 5-man will still be a yardstick against which to measure, because the Kamau will still be the best at ARO, but the Hsien would easily sail to the king of active round because BS 17 B5 HMG fire with MSV2 and smoke access (from a Haris, no less!) is superior to essentially everything - and it'd have Deflector L2 from the Zuyong - AND it'd have strong melee support with Stealth shenanigans from the Crane! TLDR: Kamau is a yardstick because it's great in ARO, not because it's great in general.
I was about to say something about the active turn then remembered the Rui Shi is a more accurate MSV2 core linking unit with the same burst in Dahshat.
Rui Shi is just as accurate as the Aquila with +1B from the spitfire, and it has access to smoke. Who knows what the decision process was on that for Dahshat.
But Rui Shi is far less durable than the Aquila Guard, and quite difficult to hide/keep safe if going second or after turn 1 use. Maybe it's what make them decide it was acceptable?
Yeah big base and inability to prone matter a lot when it is an active fireteam looking for positioning. Corregidor players experience it a lot these days when their Tsyklon omg18bs murder machine gets chainrifled and becomes a conductor for shotgun templates once reactive turn begins.
Also shorter range, has an order tax to put up assisted fire, can't dodge for toffee, 0 ARM. The Rui Shi is a complete glass cannon whereas an Aquila/Hsien HMG is much sturdier.