I'll make this quick… I reached out to Dan over at Hockey Wilderness (SB Nation site) to get some info about Johan Larsson and Matt Hackett. Here's what he's got on both players:
Hackett is a solid sized goaltender with great reflexes and smooth movements. He's aggressive in the crease and an extremely athletic player who is strong in the crease.
His main weakness is his rebound control as he sometimes gives off juicy ones from his athletic style. In addition, he has battled with inconsistency issues this season in the AHL, but he has succeeded at every level he has played at.
He is ready for a NHL backup role and with a bit more development to secure a starting position. He has proven himself at the AHL Level and has proven to come up in big games. While it wouldn't hurt for him to go to the AHL for another season, it is not like he HAS to be there.
Larsson is a competitive forward that's gritty and hardworking. He is very athletic, well-built, and hard to knock off the puck. He is a very versatile forward who can play in any situation, great on the cycle, and is just a battler. He has some solid play-making abilities and can work in traffic.
He isn't a power forward or a mean player, but he is player that can go into the dirty areas and into traffic with confidence. Just a hard working player with solid size. His total offensive upside is questionable, but he has the potential to be a 2nd/3rd line versatile forward who plays in all situations.
Larsson is having a solid year in the AHL and if you put him on the 3rd/4th line of any NHL team, he wouldn't be too out of place. However, if you really want to see if you can develop his offensive upside, he would be better served at the AHL level for now.
You are getting two great prospects.