SEVEN: Do you think I'm disgusting?
IKO: You've been nothing but kind to me.
SEVEN: You asked me earlier if it hurt when my occipital implant was installed. I told you I didn't remember. But the truth is, it was one of the most painful experiences of my life.
IKO: Why did you lie?
SEVEN: It's difficult for me to talk about, because I forced others to undergo the same procedure.
SEVEN: I was compelled to do so by the Borg Collective. I wasn't in control of my actions, just as you weren't in control when you took
a life. My nanoprobes have given you control. You're a different
person now. You don't deserve to be executed.
As for the Borg after assimilation, I'd say again yes. The Borg wouldn't care if a Drone is in pain as long as it does its job (no local anesthetics here)
EDIT as for them not 'flailing around', remember they don't have control after the nano-probes are injected. Think being operated on while you're paralysised but still awake (Picard managed to shed a tear in TNG:Best-Of-Both-worlds. Drones is a good word, the Borg don't care as long as the Drone functions