Aww hell, heres my $.02
I have and use a task-killer.
My M-O : NO AUTO-kill. When i do my screen unlock sequence i hit the task-kill widget. (i do have some minor apps ignored(clock/calender stuff)) So whatever was running is out. i dont care what was preloaded, i want all mem available. i dont need the processor taking up time/power thinking what old app to dump? It only needs to use its resources for MY commands. If i know im not going to be using my phone for more then an hour i'll hit the task-kill widget and let some apps restart if they chose.
However when my screen is off these apps are limited to only using the CPU @300, so their effect is minimalized.
I use my fone a good amount (in my mind) and i have great batt life.