“I’m not sure we’re on the same page with that concept.”
IMO only means “I disagree”, and implies much more a difference of values than of cognitive capacity.
“This is counter to my current understanding”
„Interesting idea. Let’s put it in the backlog for now and come back to it nev—I mean later.“
Have you tried looking at it from a different perspective?
Understandable. Have a nice day
“Yeah, I don’t know about that”
“That certainly sounds very … courageous”
Too mild, i need something stronger.
That’s not a bad idea. However, I would propose a few small improvements to - completely different plan follows
sound like you have implicated a whole lot of mental gymnastics for that.
“That’s not a reasonable [opinion/position/take/xyz] and is going to [cost us money/make us look bad/blow up in our face/etc].”