There is also the fact that the kannon has a visual showing its charge and you can roll/jump dodge the shot. If you go in spamming and don't outplay them don't expect to just win. I mean you could even have just shield blocked the shot and beat the guy to death.
One of my friends goes Kannon quite often when we need to linebreak a defense and he's pretty good about it. Especially when he's in a obscure location. However in almost all cases, when someone gets up close to him, he gets his ass kicked or blows himself up. I've fought kannon boyz a bit and honestly their not too difficult. It takes some practice to dodge a close range kannon shot but in most cases I get to strike the boy before he even notices I'm behind him. In contrast with the old Plasma Cannon, the Kannon is a breeze to deal with once you know where their firing from as bulk of them NEVER check their backs. If you don't wanna melee them then take a suppression weapon and fire in their direction since kannons can't aim for crap when being suppressed.
In the current game state, most people with a ranged weapon can kill you before you get the Kannon charged to fire. That's assuming your remembered to reload (unlike me). In that video, you can see the Kannon reloading (where the muzzle is pointing down), and starting to charge as the Marine was heading toward him. It takes what, 2.5 seconds to charge? The spam attack after killing the first guy is what really killed you. How do I know? You both died to the Kannon shot, and had you been .5 seconds faster, you would have killed him. Which means the unnecessary attack cost you the time you needed to survive. To be fair, I've done the exact same thing. Killed people at point blank range (including myself). The reload/charge time however, means I was ready for it long before they got to melee range. When someone comes charging at me to melee, I spam the hell out of my grenade button, hoping I get it thrown. I typically don't. If someone starts shooting at me in close quarters, I spam the hell out of my grenade button, hoping I get it thrown. I typically don't. In close quarters, having a Kannon is usually detrimental. To me.
Suppressed kannon...probably the worst feeling way to fight in the whole game. You will randomly shoot a wall or the ground directly in front of you.
Yeah Suppression is absolutely ruinous for a Kannon Loota. Just one shot from a Heavy Bolter in our vague direction and suddenly I'm aiming at the sky or the wall or whatever. Why that strategy isn't used more often in place of complaints is confusing. Literally, you see a Kannon? Suppressive fire and send in a JPA/GA. Trust me, you'll do fine.
Kannon Loota is what I roll with when I want top score in a match without putting any real effort in. It's amazing for playing hungover. If someone comes to melee me, then it's only an issue in that short period while I am reloading. Any other time I just shoot my own feet and get one more kill before I respawn with the Kannon again. It does have some downsides as a weapon, but these are almost irrelevant because of how good it is where it counts. It's ability to insta-kill large groups of players at range are unsurpassed and make it easily the best heavy weapon in the game once someone learns to work around its few foibles. A good kannoneer wins games almost by himself. If I didn't have a terminal stormboy addiction I would use nothing else.
As long as i have my Napalm Kannon, and can use it grenade launcher mode...i'm good ^^. Agnatio B, when they are all krumpd up on that balcony...is such a nice spot to make some bouncing shots of burned carnage. When playing against orks.....to be fair....i don't recall beeing killed by kannon that much.
When I'm kannoneering I focus on the areas that people tend to clump together in, for maximum kill-farm. If you play smart and do a lot of flanking in your usual play style, then you wont get hit by kannons often.