Here's an interesting exchange between a user and the author of this article from the comments. Sorry for the length, but I think it's worth reading. I happen to fully agree with uberrob.
uberrob:
Aside from being poorly written, most of the assertions in this article don't make a lot of sense. The "Task killers save battery - FALSE" argument, for instance, is missing the point: it's not the removal of the task from memory that is saving the battery, its that stopping the task releases resources consumed by the task: CPU, radio, GPS, etc. Stopping a task *absolutely* puts less demand on the battery because that task is no longer putting demand on system resources that make use of power. Similarly, killing a background task reduces competition for resources, CPU and memory - all of which causes the remaining tasks to perform faster thereby speeding up your system.
Automatic task management happens in every operating system, including android, but it does not catch or maintain the system in every use case. External task managers and "task killers" are perfectly acceptable forms of manually managing a system,
Bizarrely, this "you shouldn't use task killers" article ends by recommending an application that is, in fact, a task killer.
This article is just...strange.
Rachid in reply to uberrob:
Thanks for the feedback

It is far better to use the settings available in an application to manage its background use of things such as GPS and background data transfer. A good app will include options to manage this. Task killing is not supposed to make up for poor app implementation...
So of course, if your app does this in the background without the option to manage it, then killing it DOES save battery, that goes without saying. It also goes without saying you should look for a better app to replace it.
Hope this has cleared up your first point.
Second point, I hope I explained how android was developed, with the idea that the user should not have to worry about killing tasks, please re-read the article if you didn't get this point.
Thirdly. I think you are mistaken about what I suggest SystemPanel should be used for. At no point do I say you should use this in the typical way a task killer is used. Instead I point out that if you have memory issues, a bad app may be causing this, and you can use SystemPanel to find and then remove this app from your phone.
Just to clarify, SystemPanel was never created to be a task killer, and my instructions in this article do not advise to use it in such a way.
Hopefully that has cleared up any problems you had understanding this article, please do let me know if you need anything explaining further, I can try to simplify it
uberrob in reply to Rachid:
Honestly, rachid - you really don't have to "explain" or "simplify" things to me. Trust me, I understand what you are saying - but your assertions are just incorrect. What you do have to do is to stop spreading misleading information about systems management.
Again: task management and background task removal is a completely acceptable way to manage your handheld - OSes do not know what is happening inside a given application, and often give it the "benefit of the doubt" and let it run. Also, its not just "poorly written tasks" that appropriate resources and never free them up.
BTW, you should re-read your own article. You most certainly do recommend SystemPanel for stopping what you call "poorly written applications." In fact, the entire article, as well as some of your rebuttals to peoples comments, is littered with special cases: "Well, if you have an older device, use a task killer." or "if the application is poorly behaved, use a task killer."
Android is open for a reason, and its a manageable operating system in its own right - do what you like to keep your phone running smoothly.