I think the stuns are pretty balanced in principle.
Taser: low AP cost, cannot miss, Fortitude Check
Dirty Kick: medium AP cost, can miss, no Fortitude Check
Electrokinesis: high AP cost, cannot miss, no Fortitude Check (or it's very hard to resist it)
However despite this intial appearance of balance, Dirty Kick kinda sucks though compared to a Taser for having lots of less obvious weaknesses:
- uses up a whole feat slot instead of a few skill points
- much bigger cooldown, no less than double, and very high quality infused boots can merely reverse this instead of going further
- mechanical damage is much more likely than electrical to be fully absorbed by human enemies' armor, preventing the stun
- does not work on mechs at all
After all that the fact that it can still miss and has a higher AP cost than a Taser kinda gets on your nerves.
I only used Dirty Kick for my String Lord crossbowman because I absolutely needed all the utility slots free for different types of elemental bolts, I definitely didn't enjoy the numerous drawbacks it had over Tasers.