I think the ellipses are fine, but I agree with the comment from the original site that italics would work as well. But neither one really shows a question, to my reading.
If you mean for someone to be emphasizing 'different', I'd use italics.
"He's a different sort of person. Not like the others at all."
If you mean for someone to be using 'different' as a sort of code for 'strange' or 'unappealing', I'd use quotation marks.
"He's a 'different' sort of person. Not our sort at all."
If you mean for someone to be struggling for words, I'd use ellipses.
"He's a... a different sort of person. I think that's what I'd call
him."
If you mean for someone to be questioning whether he's really different, I'd use a question mark.
"He's a different sort of person? Is that what you're saying?"
If you mean for someone to be focusing in on the word different, while still asking a question, I'd combine things!
"He's a different sort of person? Is that the word you'd use?"
Are there other possibilities? Probably!
He's a _different_ sort of person, I suppose,
, or"He's a different sort of person, I suppose," said Keith. He paused on "different" when he said it, making the word sound like a question, and hardly a subtle one.
Punctuation only goes so far :P