I have this recollection, though I might have dreamt it up, that there was a point in S6 (or somewhere) where somebody questioned Ben on his decision to house the Others in the barracks while the rest of them lived the simpler life up at the Temple. Did this happen? If so, when?

It doesnt have to be a conversation with Ben, I just want to know if this topic was touched on.

Not sure about Season 6, but the following is from 'Dead is Dead'.


[The "PROCESSING CENTER" sign hangs swings from its single remaining chain, making a metal creaking sound in the night.]
LOCKE: So whose idea was it to move into these houses?
BEN: Excuse me?
LOCKE: Well, your people were living in the jungle. And then after you murdered the DHARMA folk, you relocated here. I just wondered if it was your idea.
BEN: Do you disapprove, John?
LOCKE: It just doesn't seem like something the Island would want.
BEN: You don't have the first idea what this Island wants.
LOCKE: Are you sure about that?
[at one of the houses, a light turns on]
LOCKE: That was your house, wasn't it?
BEN: Yes, and that's Alex's room.
LOCKE: Well, I suppose you better go over there and check it out

And the following is from 'Meet Kevin Johnson'.


[Alex and Karl turn around. Rousseau comes nearer to hear the conversation.]
BEN: May I have a word with you?
ROUSSEAU: I think we've heard enough from you for one night.
BEN: I'm sorry, you're just gonna have to listen to a little more.
ALEX: It's okay. What do you want?
[Ben takes a piece of paper out of his pocket and unfolds it.]
BEN: This is a map to the temple.
[Alex takes the map.]
BEN: It's a sanctuary. It may be the last safe place on this island.
KARL: How come we don't know about this?
BEN: Well, it wouldn't be a sanctuary if I told everyone, would it? The rest of our people are already there. If you leave now, you can get there in a day and a half.
KARL: If it's safe, why don't we all go - Hurley, Claire, the baby?
BEN: Because the temple's not for them, Karl. It's only for us. These people that are coming - they know who I am, Alex. They're here to capture me. They'll kill anybody that gets in their way. If they knew who you were, that you were my daughter, they would use you to get to me. We don't have much time.
KARL: Maybe he's right.
ROUSSEAU: I agree. We should go.
ALEX: These people - you said they're dangerous. More dangerous than you?
BEN: Yes. But your mother will protect you. (Lowers voice) Okay, now go.
[Alex, Karl, and Rousseau leave.]

Thank you so much. I forgot about that conversation in Dead is Dead.

EDIT: Do you get the impression that some of these Others (like Dogen and Lennon) were already at the Temple long before Ben sent Alex there?

You're welcome.
100%
EDIT: Do you get the impression that some of these Others (like Dogen and Lennon) were already at the Temple long before Ben sent Alex there?

I'd like to think so, but I suspect we'll never know now that Dogen and Lennon are dead.