There was quite a lot of work by Aagaard and his quality chess book on 9....c4, and this has been more recently updated by Kotronias. Don't have either book though, and not very familar with resulting positions. Have looked at more games played in the traditional 9...h6 10Be3 c5xd4 played by Kasparov a lot, and find it more active for black. Sometimes evalutation of positions isn't objective but more based on what familar with.
What do you play against these triangle defenses in the Closed Catalan
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Avrukh mentioned something that surprised him with Tarrasch lines. I wasn't wanting to go hunt for it, just thought maybe it was specific IQP positions. But since I was looking at another Black IQP line (self imposed below), I might as well.
Black is behind in development. Not sure what the urge for this IQP would be.
With zero pressure against d5, white has nothing special here. He has securely controlled d4, but he lacks an active plan.
I won't argue that!!!
I would guess c7/c5 squares, trading down to an endgame might be enough though?