DOW2R: Why is the Leman Russ Vanquisher Cannon upgrade so crap?

[mlai]

I know I'm a few years late. But I stopped playing R for a long time in the middle, and IG is the very last faction I started playing.
So the Vanquisher upgrade is supposed to be the anti-vehicle option, and the plasma cannon is the short-range anti-infantry AoE option.
At first I bought the Vanq for dealing with enemy vehicles. But it didn't give me any appreciable results. My Vanq-equipped LR was driving around chasing Fexes, and doing piddly damage.
So I bought the plasma upgrade, which is incidentally the same price....

Anti-infantry: Friggin' godly. Rapid-fire AoE anti-infantry dps! The short range hardly matters, because your biggest anti-veh infantry threat will always be the melee troops (Bloodletters, Ogryns, Stealers) or the short-range anti-veh troops (Kasyrkins). The plasma cannon is perfect for gibbing them single-handedly while your tank backs off in reverse. Saved my tank's skin more than once.
Anti-vehicle: Friggin' godly. A dreadnought was chasing my tank as it was backing away. 1 volley of several plasma shots reduced its lifebar by around 50%. Short-range? Not really. I win shootouts vs enemy tanks half a screen away, with the plasma cannon upgrade. Do I actually need sniper-like range? Not really. I want my tank's machine guns and lascannon to be useful too, after all.

Is my impression correct and the Vanq upgrade is just crap?

[Codex]

The executioner upgrade I find kinda meh. For one it can do friendly fire to your infantry IIRC, or at least the LG's executioner turret can.

The vanquisher, on the other hand... if you've ever played COH with British, treat it like a Sherman Firefly. It has a really great punch from long range that is beyond retaliation if you use a spotter. It's also durable, which allows it to fulfil a kinda Fire Prism role without being so vulnerable and requiring micro all the time.

The main thing I find about the executioner is that its ideal engagement range is much shorter if your opponent is making moving targets out of everything instead of just standing still.

[Arbit]

A lascannon pred and maybe even the basic cannon pred/looted tank/Leman outrange the executioner. This is a pretty big advantage because if he is smart and kites a bit, you are forced to move forward, potentially exposing yourself to all sorts of nastyness like a pre-setup lascannon, beamy lootas, etc. Also, if he moves around a bit at long range your shots will miss due to the travel time.

Also, heroes. The executioner is not good vs small single figure targets as it relies on AoE to inflict its damage on infantry targets. Against a single target, it does a rather puny 18 damage per shot and tends to miss a lot, not to mention it has a minimum range (with melee squads, stragglers can still get shot - not so much with heroes). The basic cannon can knock off a decent chunk of HP in the first 5 or 6 seconds - two shots is about 200 damage.

The vanq upgrade removes the AoE damage the basic cannon has, making hitting infantry targets a little iffy (80% accuracy). Basically, you pay extra to turn it into a long range tank hunter.

I usually just leave it as-is. If IG had a unit with huge sight range like scouts I'd probably use the vanq upgrade.