I talked to a friend of mine about them and he works for a company as an IT specialist. He said task killers will kill the phone over time and here is why:
Your friend must be tier 1 support, and has no idea what he's talking about.
1. All programs are running for a reason, be it reading or writing. To kill the programs can destroy them.
The "reason" half of the programs are running is because I launched them. As far as I'm concerned, if I'm done with the app, I should have the option of cleanly quitting it without it running in the background for absolutely no reason.
As for killing them destroying them, that's BS. A program gets loaded from storage (sd, hard drive, etc) to memory. It runs in memory, and when you kill it, you kill it from memory.
Now, it's absolutely possible that an app could be writing to a file, and killing it could cause a short write (incomplete) thereby corrupting the data, but that's a far cry from destroying.
2. You just killed the apps. Prepare for lag and fast battery drain, because these apps are gonna all start back up at one time to finish what they were doing.
Not at all true. If I kill the browser, it won't start back up again until I launch it. SOME apps will auto start, but those are typically OS services and probably shouldn't have been killed in the first place.
I will say that some task killers are better than others, in that they shield you from the stuff you shouldn't be screwing with, whereas others are more like power tools, and let you kill things that you shouldn't touch unless you really know what you're doing.
3. Android is like Linux. It will shut down less used programs to keep the memory from getting low.
Android IS linux. I agree that it shuts down less use apps, my argument though is the min RAM setting is too low. Once it starts to shut down apps on it's own, I've already been lagging and stuttering for more than I care to deal with.
In the end, he said, get rid of task killers, unless you want to keep buying a new phone every few months.
I defer to my original statement, your friend has no idea what he's talking about. This is as bad as saying don't run Task Manager on your Windows machine unless you want to be buying a new computer every few months.
Tell your friend to go back to screen door sales.
Now, I realize that OfTheDamned and I may differ on this matter, and that's absolutely fine. She's got way more street cred here than I, but I think she'd agree that most of the reasons posted above for not killing apps are just ludicrous.
Doc