Back to the original suggestion. So if some psion was hurt; you'd want them to have the ability to deal damage to another player AND heal themselves? My first thought is that this would be a highly overpowered ability. Secian transfer heals a person while dealing damage to the secian. If you'd want this more in line with reverse secian transfer; then I'd suggest an ability more like this:

A psion is down some amount of hp. That psion can at some psi cost deal damage to another being while taking some damage at the same time. Its more like a self sacrifcing psi ability. I'd also leave it so that the power of this ability grows the more the psion gets hurt. That would make it more interesting and a true kamikaze attack versus say replacing dart or bolt.

Also, the whole tradeoff system seems more in line with current changes in DGate like stances.