I must say Spartan has impressed me. Over the years I have tried quite a few anticheats out there, and the bulk of them are either easy to bypass, or simply poorly designed in that they produce way, way too many false positives.
Now, avoiding false positives 100% is completely impossible. You will always have SOME false positives. It is how the plugin deals with it that is important, and this is one of the elements that Spartan Excels in.
It stops all the usual things, and stops it very well. We're always bothered with hackers on our server, which I am sure you are on yours as well. Spartan does great against the best out there. The plugin is around 200k in size, and certain others (also good) plugins have already busted the 2mb mark, so make sure you consider Spartan for a light-weight, heavy-duty AntiCheat.
Developer is very active and maintains the plugin very well. Frequent updates (which is good!(don't ever complain about that)), and very helpful. He has always been quick to respond to requests for help. Beyond what is expected, if you ask me.
We are using it as our daily driver where hacks are concerned.
First of all, if you are on the fence about purchasing this plugin... GET OFF THE DANG FENCE. This is an insanely good Anti-Cheat for a price that is a fraction of what its worth. Trust me, I have tried coding a custom anti-cheat, and it's simply not worth it. This blows NCP, and any of the other AntiCheats I've used out of the water. Running this plugin's API, which is great, and our game and core plugins, we can host an entire lobby with 20 players and 100 TNT going off a second, with less than 300MB of RAM. (In other words, it's very well designed, and light weight.) This plugin is super customizable, but the default settings work great, so 90% of the time you don't have to do a thing. (A few false positives here and there, but that's to be expected, and its getting better with every update.) We've put it up against at least 10 of the best hacked clients, and none of them get away with anything. WURST, Saint, Wolfram, Carrot, Huzuni, Impact, FusionPloit, SkillClient, you name it, it doesn't stand a chance. But wait, there's more! The best part about this plugin isn't even the plugin itself. It's the developer. The Anti-Fly check was incompatible with the Double Jump code we used on a lot of our servers, so I contacted the guy who made it, even though I knew that Double Jump was listed in the plugin description as something that may be incompatible. Within 20 minutes, he got back to me, asked more about my problem, and sent me 2 different snippets of code that he thought might fix it. When that did't work, he updated the plugin twice to fix the issue. The guy is exactly who you want making your plugins. Active, helpful, smart, and dedicated. I would give this plugin 10 stars if I could.