Chainguns are harder to fight with lisk than lucis, and this is especially true when given a luci suit compared to a chainsuit.
With a lisk, it's almost impossible to get hit by a luci if you're being smart about your movements, and so all it takes besides that is patience. Once you get on top of a helmeted luci's head, just jump up and down while swiping their head and so long as your HP isn't TOO low, it will take a good bit of splash damage to kill you, enough that when I manage to get on a luci's head efficiently, I take them out probably 75% of the time. Even the overcharge technique often doesn't work, although servers with higher knockback will cause you to get thrown off more often than not.
As for suits, the immediate reaction after being grabbed is generally not to look up. I've had suits, even good ones, severely injured before they look up.
Chainguns though, they're a bitch to kill with lisk. Getting close is tough if they're shooting at you, the knockback affects lisks tremendously. Not only that, but lisks don't have to HP to stand up to even a mediocre chaingun user. Unlike lucis, you can't really be CAREFUL about your movements because so long as you're where a chaingun can see you, you can be hit, so you have to rely on quick movements instead of easily dodging a luci. I only lisk a chainsuit every now and then, but the best way to lisk any suit, except luci and flamer, and maybe saw, is to run evasively around them, making sure to keep your grab by keeping a lock-on to them, and make quick reversals in your movement patterns.