As you know, I'm pretty much a PvE player, not an STFer or PvP, so take this for what it's worth.
I've played around with the Hargh'peng torpedoes and haven't found them to be as useful for me as a good Tricobalt Torpedo. I realize that the Tricobalt is slower getting to its target, but I've seldom had problems with any of my opponents shooting them down. If I remember correctly, the burst damage is about three times that of the Hargh'peng, so even if I only land a third as many shots, i do at least as much damage as with a Hargh'peng. Also, as far as i know, the Tricobalt is able to gain a boost from the Torpedo High Yield DOFF power. I've used them in a forward weapon slot to break down enemy shields and I've also used them in an aft weapon slot on a broadside boat to deliver a major punch when I shift from port to starboard for my beam attacks.
For those who may not be aware, the Hargh'peng is not only available from The Doomsday Device, but can be crafted at Qo'nos by KDF players who have enough of the right data samples and a small fortune in Dilithium to buy the required UMs. The crafted ones are not bound, so they can also be picked up on the Exchange or received in trade from another player.
KDF can also get them reasonably easily via a Doff mission.
I wonder what it would be like on a torp volley......... will have to get mine out of storage for a quick try
I suspect you'll find better damage with Fire at Will, thanks to having multiple beams being able to broadside repeatedly. Beam Overload is usually better with a high-damage escort and dual beam bank, aiming for spike damage. That's my understanding, anyway.
Hargh'Pengs are good, otherwise. Especially if you simply can't spare any torpedo skills. The cooldown is high - not sure if torp doffs are worth it. I'd be tempted to just stick them on autofire and then forget about it.
I have found a high yield tricobalt III to be highly effective, especially on slow moving Oddyseys.
First engage with full power to weapons with Tac Team I, Fire on my mark, Attack pattern Alpha, Go Down Fighting, Tactical Initiative and hit the Cannon:Rapid fire 1. Let the rear 3 turrets do their work with full power shooting forward onto enemy shields for the full ten second duration.
Then hit the Beam overload which will use one of your 3 dual beam banks.
By this time the global cooldown from Tactical Initiative will make Tac Team 1 available again. Activate along with High Yield 3 and launch the Tricobalt. Keep heavy fire on the target keeping the shields down until impact.
Tactical Initiative should still be cooling a 15 second window to use high yield 3 again as you slowly turn around and then launch 4 quantum torpedos from Aft.
This tactic is usefull also with just Quantums installed fore and aft and makes tons of agro even with a zero ranked threat control.