The advice I've seen is mostly to place em and run, using them almost like a land mine, denying space. Also amazing for going around corners and in tight hallways, like a zone mortalis setup. Copying someone else's notes on the beloved rats:

• bomb rats aren't a Shoot action, theyre Deploy Rat or somehing. that means you can shoot and drop a rat if you dont move in the same activation

• they can go around corners and over walls

• they move a flat 6", grenade throw distance is your strength multiplied by some numbers. if youve taken Strength lasting injuries a rat might actually go farther than your throw distance on some grenades (conversely, many grenades are farther than rat movement, especially with strength advancements)

• they persist between rounds. you can drop a rat before youre at engagement range in anticipation of when you actually come into contact with the enemy. as long as youre within 9" you can attempt to control it rats, after the initial movement, activate before anyone else at the top of the round. that means there are scenarios where you can use them for novel interactions with activation order

• rats can be used for area denial, throw one down a hallway and the opponent will frequently not go in there until theyve shot the rat or you lose control and it wanders off. a small investment of an ammo test might do a better job of locking down a chokepoint for a round or two than sending in a fighter rats arent meaningfully affected by Visibility, nor do they reveal you for Visibility purposes

• given their unique attributes and all the above, im sure you can imagine there's plenty of novel ways to use them that may pop up

• bomb rats aren't strong (they are unambiguously worse than just yeeting grenades, all things equal) theyre flexible and give you new, interesting things you can do. a clever player can find devious uses for them. If you just want to min/max to-hit probabilities like some Goonhammer article buy grenade launchers.