I totally get tempering enthusiasm on any prospect - especially after how high I was on Grachev back in the day. But you're being a little bit disingenuous with your comparisons here.
Yeah, Dawes had 47 goals as an 17-18 year old, but the more complete story is that he was 47-45-92 in 72 games. And then he went 47-23-70 in 56 games as an 18-19 year old. Neither of those comes CLOSE to Duclair's current tally of 50-49-99 in 59 games as an 18 year old (who doesn't turn 19 until a week or so before the beginning of his next season). As for Christian Thomas, he's closer - he went 54-45-99 in 66 games as an 18 year old. But, that's still 12% less.
Both also had significant size issues, which Duclair does not, and neither one of them was blessed with his skating. Those aren't things you can gloss over, they make a big difference in projecting a prospect's likely success.
Duclair is a legit top prospect at this point. Of course there are questions as to whether or not it'll translate when he moves up the ladder, but that's true of everyone not picked in the first 2-3 spots of every draft.
Butchy's progress against grown men is also encouraging, so he's got the benefit of having taken a step that Duclair hasn't yet - but then again, will he have issues with the NA sized rinks? I don't think so, but it's a possibility.
I am cautiously optimistic about both - and you can make a very good case that both would be first round locks if they were available in this year's draft.