As of right now, I feel Psi Ops are a complete waste of a slot which could go to some other far more capable class. My suggestion is to get rid of the class entirely and go back to the days of EU/EW. Let us train Psi abilities on any regular soldier like in the good old days. If there's a way to implement a trigger to decide if a soldier is gifted or not, all the better (all soldiers getting Fortress/Bastion may be a bit strong).
Next, make the abilities usable without a Psi Amp, but make it possible to switch out any secondary weapon for a Psi Amp for the extra boost (I wouldn't do this with a Grenadier or Technical).
While it may take a bit of re-balancing, most Psi abilities only increase a soldiers utility (other than Fortress/Bastion anyway). I'd much rather chuck a grenade or fire a rocket than use Void Rift, and I'll usually have an extra Shred Cannon or Saturation Fire that's far more useful than the 2 or 3 enemies I can line up for Null Lance.
EU/EW did it right. You trade extra time in the tank for a more well rounded soldier. Psi Ops in their current iteration are in a sad state. Even if I could train every ability, I'd consider them a liability.