From perspective of PVE player (mostly flashpoints, uprisings, SM and occasional HM ops, and difficult solo content):
As someone who loves Mercenary (especially healing discipline), I wasn't happy with these changes. To me, Mercenary is about good survivability, individual utility and mobility, even if their damage and energy management could be better. Seeing their advantages downgraded (we now either have to choose between mobility and survivability or have less of both in general) without giving much attention to their weaknesses, I'm simply disappointed.
More on this:
With the idea of having less abilities, I was surprised to see Missile Blast and Electro Dart. Those abilities only have situational use for IO, and even that is arguable. Would I rather use Missile Blast, that does more damage and costs 10 less heat under 30% health or Power Shot that generates a stack of Supercharge? I'm more for second option. And Fusion Missile does exactly what Electro Dart does, if not better (with only downside of having cast time, which can be solved with Power Surge). So every discipline can live comfortably without these two, so why not take them away? Or at least merge them with something else.
I understand that you're trying to balance defensive CDs for all classes, and since I am yet to try PvP, I don't mind it, as long as we still can have enough DCDs for PVE content. But having limited choices on mobility really threw me off. I like to take Thrill of the Hunt and Power Overrides (especially on Bodyguard) because it gives a lot more mobility. Now, if I take these two options, I lose threat drop (and I don't understand why is threat drop an option, especially for healers) and a good upgrade for Kolto Overload (but I can live with that if taking Responsive Safeguards, but then I'll lose Hydraulic Overrides, which is very useful in combat).
Now, my biggest complaint is having less tools for energy management. IO is known for being one of the most difficult disciplines (if not the most difficult) in terms of energy management, and Bodyguard spec has more energy management issues than other healing specs (in my opinion). Now, with TSO being merged with Vent Heat and not having some utilities that helped with that, I'm not sure how are these two specs going to manage. Arsenal seems to be fine, plus having an option that reduces the cost of Tracer Missile (the most frequently used filler). But IO with its constant use of TSO is going to lose in damage, having to use Rapid Shots instead of Power Shot to save heat generation. I suggest keeping TSO a separate ability, but if you absolutely have to merge it with something else (don't understand that), it's probably better with Power Surge than Vent Heat. In rotations I use, TSO is only used with Unload, Blazing Bolts or Progressive Scan, and none of these abilities have cast time, so they won't affected by Power Surge (if PS and TSO are merged). But if using Power Shot, Tracer Missile or, say, Rapid Scan shortly after this (which is often the case), they will be instantly activated. Seems better to me than waste Vent Heat until absolutely necessary.
And second thing on heat management: why not give an option that Heat Damping utility provides (cleanse, Jet Boost and some other abilities don't generate heat)? It is very useful for Bodyguard and could also be used for IO, if Jet Boost generates 2 stacks of Supercharge. Maybe have this replace Electro Dart.
Lastly, while other classes seem to gain a good upgrade in either DPS or healing (can't say anything on tanks), Mercenary lacks that, though Arsenal seems to be fine. When I saw upgrades for Dark Infusion and Innervate on Sorcerer and Kolto Infusion on Operative, I was excited to see what upgrades Bodyguard would receive. And when I read about them, I was disappointed. The AOE option for both Healing Scan and Kolto Shell weren't that good (compared to Sorcerer and Operative), the rest option for Healing Scan didn't seem to be very useful, but I can say with little upgrades, the other 2 choices for Kolto Shells could be good.
For IO, the choices seemed to be ok until I saw what was offered to Pyrotech about Incendiary Missile. Seriously, if IO options for Incendiary Missile are replaced with Mandalorian Warhead, Primed Rail Shot (just with Mag Shot), modified the third option and TSO is a separate ability, IO will be in a much better position (IMO).
Overall, did it feel like Mercenary? Not really, with less mobility, survivability and not having better new options for damage, healing and energy management.
Then again, I'm not a NiM raider or PvP player.
