Montour could go down the road of Brennan. But that's true for any prospect, there will always be statistical comparables that failed. That doesn't mean that the achievements are not worth something, both in themselves and as an indicator of offensive upside.
There's usually no reason to throw out useful information other than when you don't like the conclusions that they point towards, and is unwilling to consider changing your mind.
The chance that someone that does what Montour has done becomes an impactful player is good, bigger than the chance that someone that does what Nielsen, Dermott or Kapanen has done becomes an impactful player. If the odds and projections favor a prospect over another, he's likely the better prospect.
Naturally, the evaluation shouldn't end there. Kapanen for example played down the lineup a lot considering he was a teenager on a powerhouse AHL team, so raw numbers might not give an accurate picture. Likewise, an evaluation of Montour shouldn't stop with just his ability to produce at the AHL level.
The thing is that the further you scout up Montour, the more it just confirms the picture. He's an absolutely terrific young player. Incredibly smart, great skater, terrific offensive instincts. Very very good at moving the puck out of his zone. Could stand to work on his ability to win pucks, but he makes up for this a lot by reading the play very well.