Tech Support isn't needed in resistance. Waves usually don't last enough to make it worth while to tie up the character talent spot. Strike back and Triage for example is of better use. If the box is coming to an end, manually blow it up for the group over-heal and increased skill haste.
In resistance, change the mindset you need kills. Focus on heals and coolheaded use for Sig skill. This build will carry you well past wave 50 while using the available support station while clearing emp waves
Your largest threat is dealing with rushers and surviving emp waves. Known rusher waves, switch out SRS for a talented/self preserved house.