Spawn are the best unit to guard an ic because they synergize so well with our strengths.
Our sorcerers can innately access Biomancy and Telepathy, the first can give the squad feel-no-pain, the second can give shrouded and stealth. Both make the spawn the superior recipient due to having more wounds to take FnP on, and the easy access to terrain to counteract not having a save. I've never had a game where spawn haven't delivered the payload ic where it needs to be.
Bikers, on the other hand, are superior at being more tactically forgiving, they dont hit as hard but have lots of saves, more movement, and firepower. They are excellent flankers and transport-removal. That being said, they aren't scary at all in melee. They're just decently tough. Whereas the spawn(With a buff or two) are point-for-point three times as tough and much much more deadly combatants(s5 and an average of 5.5 attacks on the charge is fucking goofy).
They seem nearly equal, they just do different jobs. The bikers do better at cracking things like terminators and heavy transports. Spawn rip apart infantry like gorillas rip apart puppies, and they shred rhinos/chimeras like nobodies business. They just take a lot more planning and care to use.
I keep forgetting how hilarious my old posts are.
It's not a question of who will let me, it's a question of who will stop me.
You fight for nothing! You are nothing!