i think in the past (i3/i4) ws/pbs did tend to run and hide when quantums arrived but i havent seen that happen for a while now.
Certainly i'm like you, see a void, kill it is the instant response, more up close and personal the better, and then to essence drain their still warm corpse to show them that not only were they victims of my wrath in the living world, even in death they failed to the escape my fury 
@ExtraGonk
I tended to do it out of survival instinct rather than any kind of desire to kill. Most of the time as my Warshade I was teaming in PuGs, which meant that I really couldn't rely on the rest of the team to target the Void/Quantum with any kind of priority - my best chance of survival was to take it down myself.
As for Cysts, I can only take them down if I'm on a team of 3 or more - otherwise I can't get enough of an Eclipse/Mire buff off the Unbound Nictus to take it out.
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I'll go for them like a shot.
The few times I've tried the "OMG kill the quant!" bit is when the quant's shown up some way off, and I'm been playing team tank in Dwarf form with lots of mobs around me. In those cases dashing over to take the quant out personally would be very liable to scatter aggro all over the place, jeopardising the squishies.
What usually happens at that point is the team completely ignore me, and stand and watch as the quant 3-4 shots me into the ground... 
Well, there are still a lot of players around who have a macro to announce the Quantum/Void/Cyst´s presence to the rest of the team. Often enough this macro´s text gives you a hint about the kheldian´s intentions.
My warshade Sojobo for example says things that would for example translate as: "A Void Hunter... This will be a short fight." I think it should be quite clear for the rest of the team that I intend to handle the situation by myself. (However, I don´t mind if someone helped me out. Concentrated fire and a tanker´s taunt make things much safer. 
)
There are also still players whose macros go along the lines of "A Quant! A QUANT! HELP! HE WILL KILL ME!!!" (spammed three to four times in team chat), making it absolutely clear for the rest of the team that this special kheldian will be nowhere near the team if they don´t drop that quantum gunner first.
And finally there are those special macros... I once met a kheldian with a split personality disorder (among other mental problems with the human part). He kept talking to himself and when a Void Hunter was near, the conversation looked like this:
Kheldian part: "Oh, a void hunter. There is a void hunter!"
Human part: "FRIIIIIEEEEEND!?!?!
Kheldian part: "NOOOOOOO!"
This one made it really hard to take care of the void... couln´t concentrate on the fight while rofling. 
If it has eyes, you can blind it, if it has blood, you can make it bleed, if it has a mouth, you can make it scream.
I always went attacking them on my own first. After all the split second delay between shouting 'Void!' and then getting the 'where?' and then 'over there' and then 'behind the pillar?'....you get the idea, you'll already be dead. Better to go beat it up yourself.
Ah, well, that´s why I have a target-the-evil-guy-macro on my CoH-toons. With my kheldians I use it before almost every group to avoid a nasty surprise by some lieutenant pulling this big gun from behind his back or a cyst crystal hidden behind other mobs.
On my other toons I just use it when the team´s kheldian gives a warning or I have accidentaly spotted something anti-kheldian in a spawn, so I can provide fire support without any split second delay.
Wise players without such macros will know to target via the kheldian in question, so the question "Where?" should disappear after some levels of teamplay experience... I hope. 
If it has eyes, you can blind it, if it has blood, you can make it bleed, if it has a mouth, you can make it scream.
Aforementioned bind being
/bind [ "target_custom_next void$$target_custom_next quantum$$target_custom_next cyst$$target_custom_next sapper"
Type it, use it, love it.
Oh and for Warshades, try /bind ] "target_custom_next enemy defeated" for targettin a fallen foe for easy unchain essence and extract essence.
Back on topic, running towards Quantums is a good idea as theyr coded with Void script, hence will put away the nasty gun and try to melee you. Voids have a nasty quantum-damage glove, Quantums do not.
i find myself using extraction as my targetter for my unchain essense, works the same way
@ExtraGonk
Ok I am from the Kat/SR origin of AT this means I have suffered many a time from blows to the head. This I believe has lead to a potentially dangerous past time.
The number of times I see a kheld on a team shout VOID/QUANT/CYST KILL IT FOR ME! is numerous however my PB (lvl 34) gets a vicious urge to solo and destroy mentioned void/quant/cyst and most times after shields/BU/IS and a finishing attack the victim of this brutal surge of violence is down (cysts take longer but are doable). My WS has just hit the lvl (lvl 21) where he is semi unafraid of such things but I was curious is this just me or do other Khelds get a blood lust for the VQC's?
P.S My Khelds do have the tendency to battle VQC's until they drop no matter the odds and when soloing they continue the attack when face planted ... albeit verbally.