I agree. I wasn't saying knights will be invincible I was saying that, just like irl, a squad of knights hitting you with lances pointed is sure Defeat. Polearms are the exception of course, But cavalry with half a brain won't charge into spears. They'll let their archer friends take care of it.
Back to original topic: M&B warband is the closest to LIF combat I know/know of and In custom battle I can test out scenarios like this Relatively easily.
I hope that everyone will find their own role, with Militia Providing support and Stabbing cav, Berserkers In the vanguard and carrying out the heavy fighting, footmen Making up the stock of the battle, Cavalry Providing Devastating Strikes, harassing or running down the enemy and finally, archers, Mowin' em all down
.
Edit: how would knights be slow, a sword and chainmail is not that slow. So they could participate in sieges, just dismounted.
I hope that concludes this discussion as it is the best I can do and my argument in full.
Edit: These were footmen/berserkers style, I have a feeling only military will use militia to a large scale.