On the surface it might look discouraging. He followed a rookie season of 29 points (.36ppg) with a sophmore effort of 27 (.37ppg). In year two his PP icetime was diminished which accounts for the flat totals. If you look at EV points per 60, he had 1.33 at 19 and 1.75 this year. That's solid progress.
Cam Neely's 19 and 20yo seasons came at a time when there were 7.8 goals scored per game. In Gui's first two seasons the number was 5.6. Scaled to the scoring rate, Gui's numbers are pretty much identical to Neely's. Seriously.
Corson was more physical but had less skill.
Pyatt might be the best comp. I tried to choose guys with size but so many of them play a much more physical game than Latendresse. Pyatt is close to Gui in style and numbers. Interesting that he's playing on his 3rd team.
Brown and Frolov, being in LA, are two guys I can't say much about. The lockout year is listed for both: Brown was in the AHL at 20 and Frolov was in Russia at 22. Frolov's numbers at 20 are a little better than Gui's, but he had more icetime.
Brent Ashton is another Pyatt-like comp in that he was big but had few PIMs. He was a useful player and had a long career. Gui's numbers are better.
Kvasha is an interesting comparison because he's both bigger and softer than Lats and has better puck skill. Sanipass is listed just because it's so rare that I have an opportunity to mention a player from NB.
Graves and Doan were far behind Latendresse at the same age. Both took a long time incubating.
Most guys that look like Gui have big PIMs, that's what makes Pyatt such a good comp. Looking a little closer, Pyatt's OHL numbers were .53, 1.10 and 1.31 ppg at 16, 17 and 18. Latendresse had .92, 1.20 and 1.63 in the higher scoring Q. Gui also played on the U-18 team and the U-20 team as an 18yo.
As you can see from the list, the error bars are huge when trying to predict the future for guys like Latendresse. For now I'll go with 'Taylor Pyatt but a little bit better.'