Honestly (and I'm not trying to bash you in any way), I think making tracer missile an instant cast is a terrible idea. Here is my reason why: every class in the game can have important casted abilities interrupted (minus ravage). Interrupting TM is a reward to smart players. I cannot tell you how many times I've been casting TM, and my target didn't even bother to interrupt it; they got what they deserved, I'll leave it at that. If someone interrupts TM we are, for the most part, shut down. But the thing is, other classes can be shut down too. If you stun/knockback a carnage mara who just used gore, they're screwed. I'm not looking to make our class OP, I'm only looking for us to be on par with the other classes. But, I can agree with an instant cast power shot, and here's why: pyrotech. Pyrotech pyrotech pyrotech. It is very obvious that Arsenal has problems mobility wise, but it is also obvious that merc pyros are lacking the burst our pyro pt brothers have. Making powershot instant cast would give pyro mercs an instant ability to proc super heated rail, and add mobility to both specs. For this reason, I would recommend replacing the first tier pyrotech skill that increases alacrity (I can't remember the name of it, I'm on my phone) with a 2 point 1/2 second cast time reduction on powershot, making it instant cast. That way, both Arsenal and Pyrotechs have a chance to get that instant cast powershot, and would finally give pyrotechs a useful 1st tier talent besides the armor pen. for unload and rail shot. I play both dps specs, so I know that this would help both (I would also recommend improving the snare from cgc in the pyro tree). With this instant powershot, both specs can do damage on the run, and pyrotechs have an instant way of procing rs, bringing our burst more on par with pt's. It also benefits Arsenal mercs because if tracer missile gets interrupted, you can shoot off a couple powershots to proc barrage, and continue your damage. It seems I've gone on and on about this whole instant cast thing, so I just want to add that I fully support the addition of an escape ability, as it is much needed. Just my opinion, feel free to let me know what you think of it.
I'd much rather see explosive round get incorporated into the assault tree than charged bolts. It's already instant, and maybe lower it's ammo cost to 2, and make it proc high impact bolt instead of charged bolts.