My first few encounters with a Vulcan, influenced by the fluff-lore, had me categorizing it as one of those specialized mechs- mechs that are built for one role on the table, and in this case anti-infantry.
And in this role the Vulcan certain works well- mainly being a medium mech and have a better armor value over specialized light mechs which means it can stand up a bit more to tanks and infantry- dealing out more damage vs. received due to its weapons.
As a counter- the Firestarter also works really well against infantry, but I find it is a run in, light ’em up, and run out mech due to it’s light/armor.
I classify the Vulcan into two weapon group- anti-tank and anti-infantry.
Against tanks and vehicles we have the AC/2 which has the range to star possible scoring motive hits, and when close opening up with the medium laser.
Against infantry it has the best of both- machine gun/flamer, which one will also pelt the tanks and vehicles with.
Tactically if I’m playing an open game where the terrain would favor vehicles or numerous infantry units I’ll bring a Vulcan + my own infantry and vehicles. I don’t want to explode my infantry and vehicles on my opponent’s infantry and vehicles, but rather strip them with the Vulcan, and use my own infantry in cover and vehicles hull down to be a real pain against opposing mechs.
I also consider the Vulcan a mini-support mech, which means if I miscalculate in my lance and I’m not up against infantry/tanks the Vulcan can add some long range plinking with the AC/2 and some support with the medium laser and machinegun/flamer- maybe getting rear armor or moving in once an opposing mech has gone to internals. Certainly not a support mech, but it could be pressed into service as one.