Firstly, to answer your question about DF tier 4 talents, Fighting Spirit is a must have. DF is an extremely energy intensive tree, with the up front cost of applying DoTs as well as 25 energy Wounding Shots every 9 seconds. Without Fighting Spirit and with no Hemo Blast to provide energy-free GCDs, it is nearly impossible to do decent damage while staying in the >60% high regen bracket.
Onto the main question of the thread. The problem with DF builds in general is that the tree was designed completely in opposition to the main objective of PvP gameplay - focus fire and burst damage. DF thrives when your fights last longer than 21 seconds. If your team is bursting and focus firing correctly, targets should be dropping in less than half that time frame. In a normal fight, a 31-point DF player might have time, after applying DoTs and Flourish Shot, for one cast of Wounding Shots. What you're proposing with your hybrid build is adding another DoT to the opening rotation. Again, if your teammates are doing their jobs, that's just 20 energy you're wasting on maybe 25% of the tooltip damage of Shock Charge, and a valuable GCD that you should have used for burst damage abilities.
Sorry to **** on your hybrid build. I believe it (or some minor variation) is currently the highest theoretical sustained damage build available for gunslingers. It just has no place whatsoever in PvP.
