Engineer v Scientist

Scientists are mean. They have crazy movement thanks to 3 warps, they can heal themselves with heal thingy, and they can be devastating with the goo blaster, even at longer ranges. I know a lot of people complained about chemist in GW1 and 2 but at least he had to be 3 inches away to really hurt you. We've mentioned before that they should probably get a buff to healing and a nerf to damage and/or their ability to warp.

Engineers can be effective but part of their issue, that insane stun, has been made far less debilitating so they aren't as bad as they were. They also are tied down to the heavy helper if they want to use its full power. You can resummon it fairly often but it's not hard to vanquish (and I will focus on that turret aggressively when I see them in PvP matches). 

The station is sick when loaded up, a single cadet station (unless they know about that auto-aim exploit) isn't that hard to deal with although crater maker can be devastating, the terrain of the map can make a massive difference there. The station should not heal over time on its own, the Imp's mech doesn't and it's a machine in the same vein so the station shouldn't either. The effect of multiple cadets on a station needs adjustment, being a treetop acorn is much less effective than being a station rider. I'm not sure what they should do for the extra cadets on a station, but it's clear something needs to be done; weaker shields, shields only last so long and then shut down regardless of damage, less health per cadet, make the cadets individually vulnerable, etc. There's a lot of options to fix the station, but it has to be fixed, and soon.

As for the cadet on her own, I really can't say one way or the other. The big laser ability is effective and her normal weapon is decent, that ability where you fly up in the air and crash down has targeting issues at times, not sure if its netcode or some other problem, but it can be flakey to control.