I'm generally more interested in the Chimera than the squad.
With a Multi-Laser, Heavy Bolter and Heavy Stubber, the Chimera puts out an impressive amount of firepower. It's ideal against Guardians, Guardsmen, Gaunts, Orks, and many other similar units.
It's one more armoured target in my force. With 2 Russes, a Demolisher and a pair of Hellhounds in my force, I'm perfectly content if my opponent choses to divert anti-tank firepower to deal with them. If they don't, then I've got a good bit of firepower for a reasonable price.
The Armoured Fist squad is also useful from a force organization role. It prevents you from needing a second infantry platoon. This frees up points to spend on tanks, Fire Support squads and Anti-Tank squads. In general if you take this route you'll hit harder but be a little less durable. It's a fair trade off. As a side benefit, there's less Guardsmen to paint so you can field your force a little quicker.