I killed an A4000 by removing a battery. It was working fine, then I read a story "Leaky battery can kill your Amiga" so I thought I would remove it as a precaution. After I desoldered it, it wouldn't power up any more so I had killed the A4000 for no reason and had to buy a new one.
I would say don't bother removing the battery unless it has actually started to leak - if it looks ok then just leave it instead of doing something that could potentialy kill your Amiga for no good reason.
