how does he compare to Spencer Abraham?
Both have done a lot of their damage on the powerplay and Abraham is an interesting kid. But the main difference is size.
Abraham is an average sized defender who has had some struggles playing five on five this year (like Sproul, his rookie season in the OHL). He's also not as good of a skater. But he's definitely a very intelligent powerplay quarterback. Very good vision and has a lot of poise back there.
But his lack of elite size, skating, and defensive play make him more of a longshot moving forward. They also limit his potential.
If you compare him to a guy like Geoffrey Schemitsch last year, Schemitsch was and is better defensively and saw time on the penalty kill for Owen Sound. He has similar flaws and strengths in the other areas, but even he went in the 4th round. I think Abraham has a shot of getting drafted because he's clearly a very intelligent hockey player, but he's more the type of player you take in the later rounds.