I find I use Kolto Infusion very rarely as well. Changes I would like to see whilst leaving the skill trees as they are (albiet with all the skills working!) :
1. Kolto Infusion heals for the same value it does now, with the same lower cast time but only consumes a TA, not energy.
2. Surgical Probe consumes 1 Kolto Probe and 1 TA for X value of healing, and 2 charges of Kolto Probe and 1 TA for 2X value of healing. This X value of healing should be substantially larger than Kolto Infusions value.
3. (Slight skill tree modification) Diagnostic Scan with the 4 skill points invested would have a 5%/10% chance per tick to generate TA in addition to the exisiting perks via skills. Low enough chance to avoid abuse, but still a nice perk.
This would allow the DPS trees to have access to a fast casting zero energy cost heal at the expense of TA, while allowing healers a more diverse arsenal and more finesse balancing TA generation and spending. Using your large Surgical Probe heal too frequently would impair Kolto Probe TA generation, yet it would still be optimal to burn TA's for burst healing.
31 point skill in medical tree could also add either duration or number of stack of TA to 3 in addition to Recuperative Nanotech to make it a little more attractive.
Pick it apart please!