I ran the bulk of The Harrowing for my local group
They were set up with five 9th level characters that throughout. They were created using 15 point buy and 46,000 gp in starting wealth.
They were given opportunities to rest between most encounters.
1. Medium (Bear): Focused strongly on bear, using full attacks with his natural attacks. He was a half-orc with an bite attack and other feats to augment natural attacks.
2. Medium (Cricket): Focused strongly on cricket and constant movement. Used Kirin style with high intelligence for alternate bonus to damage. Used ranged attacks while moving into positions to charge at maximum damage.
3. Occultist: Implements were covered abjuration, conjuration, necromancy, and evocation. Following the second encounter expended resources to animate several enemy grizzly bears into bloody skeletons that followed for the bulk of the adventure.
4. Mesmerist: Half-elf mesmerist, her bold stares slowing enemies down and penalizing perception and initiative.
5. Kinecticist: Heavy focus on blasting with earth, metal (with rare metal option.) He could attack at 120 feet or in melee with his blast (although he never did the latter).
2. Bears and Stone Giant. Combat opened with occultist using a evocation focus power to create an explosion devastating most of the bear opponents (none rolls very well and all failed the saving throw). The occultist supported with healing spells following.
Mesmerist hadn't set up tricks prior and in combat looked at trying to use a trick to give ally temporary hit points, but found it wasn't a good option mid-combat.
Bear Medium played as fighter taking on bears before moving on giant. Cricket Medium hit giant after a set up turn and was crit and hit with above average rolls nearly knocking him out.
Kinetist got a few solid shots in from a distance.
3. Bear medium vs. Brambleson, the Rabbit Prince (CR 9 unique fey). This medium took this fight on himself with party providing no support with the exception of the mesmerist using her touch to remove confusion from the medium mid-fight. Bear's damage was lowered because of the enemy tactic to use Spring Attack along with having a good AC and some DR. The enemy couldn't deal consistant damage because of the DR from the medium's adamantine armor. Medium used trance with Big Sky to remove the DR as an issue during the fight.
4. Mute Hag. This was the second hardest fight in the session and might have been reduced in difficulty by me misapplying empowered to the cone of cold spell like ability. Occultist healed as the called the Open Sky again to bypass most of the DR of the hag. Memeriist threw control spells, but the Hag had a staggering Will save modifier which even after all the buffs gave the hag better than 50% odds of resisting spells. This was the one time the kinectist used the rare metal option on an attack. It got one hit in and ignored 10 points of damage and still cost the kinetist burn. Cricket medium took a significant amount of damage and had to remain at a save distance for the bulk of the fight.
5. Summoner. He used a wand of fireball, but even with a mirror image effect protecting him, he was hit times with multiple lucky attacks such that he didn't last following a second round of attacks. Bear medium was the primary damager in the fight with kinecist in second.
6. Lamia Matriarch and Cockatrices. Bear medium was charmed by lamia, then immediately charmed by party mesmerist as well. Lamia took a few hits from Kinectist as well as some from the Cricket medium and occultist.
7. Greater Air Elemental. Opting to become huge to avoid the whirlwind (rather than just ignoring DR), the bear medium tranced to become huge. All the characters had to deal with DR, and that added a round or two to the life of the elemental.
8. Denizen of Leng. Without allies to flank and sneak attack with he defaulted to attempting ability drain which failed. With strong hist from the bear medium, kineticist, and occulist undead bears the combat ended quickly.
9. Adult Blue Dragon, CR 13. This was the hardest battle of the session. The party might have been able to take this on easier as a 10th level party, but I left them at ninth level to finish off the session. Already at a high AC the dragon had a few spells to increase it even higher making it virtually impossible for the characters to get hits in. The mesmerist was able to dispel mage armor and used terrible remorse to limit the dragon's actions and reduce AC a bit more. The occulist was able to hit with a few ray attacks before having to heal the medium in melee with the dragon. The dragon attacks had almost no chance of missing any characters. The kinectist has a hard time since he still was spending burn in attempts to deal more damage while his attacks required 17+ on the die to connect. The Bear medium had a slightly better chance of hitting with multiple attacks and dealt a decent bit of damage during the fight.
2. Medium (Cricket): Used many knowledge skills throughout the adventure while supporting with bows before building to more powerful attacks. At his best his damage tended to equal the damage of the other medium, but only for that round.
3. Occultist: Honestly hard to recall exactly what he contributed. He did use evocation powers to great effect, but I don't recall him casting too many spells. A lot of his contribution to the scenario came through his healing and the undead minions he created early on.
4. Mesmerist: Hard to say but she had issues in many of the combat rounds especially when trying to set up mesmerist tricks. The false flanker trick never really helped because there wasn't a rogue in the party and there wasn't a case were an attack hit because of the +2 flanking bonus. The condition removing touch was useful, but the session saw conditions only in a few encounters. Possibly one issue was the spell list, spells were largely single target enchantment spells with non-trivial effects to relay. Throughout the several days the adventure took place I didn't get a feeling of a single standby spell that was favored. Her stare was helpful to herself, but few people in the party used had enemies make will or reflex saves aside from her and sometimes the occultist.
5. Kinecticist: For the most part he didn't have problems with accuracy, but through the adventure he seemed to be second to the bear medium who had better damage and more options in and out of combat. All of his choices improved his attacks. Increased range, expanded earth into metal, rare metal blast, melee kineticist blast. He never used the melee option, but he liked having as a backup option. Rare metal blast was an option that didn't do much. It was used in one encounter and still did significant burn to character. The bear medium had a lot easier time dealing with all DR while the kinectist dealt with metal based DR. His skills were largely limited to a knowledge, perception, and use magic device. Outside of combat he didn't have much utility at all.