A safety is a must. You can't just depress the paddle unless you disengage the safety first. I have a 3" cutoff tool that has a safety that's a pain, because it goes too far over center and takes extra fiddling to get it to release, but I'm not going to mess with it. I'd rather not cut off a finger, or even put a big gouge in one.
Another thing. ALWAYS unplug the tool before changing wheels.
[on edit} I guess if I had a battery operated tool, removing the battery before changing wheels would be a good safety practice too.
I know a guy who goes by the name of Stumpy. He repairs all kinds of construction equipment including circular saws.
He had one dropped off which the owner stated, "The switch don't work."
Stumpy placed the saw on the bench and plugged it in. Unbeknownst to him, the fool who dropped off the saw had put a wedge in to hold the guard in the fully retracted position, and did not specify that the "switch that don't work," don't shut off when you release it.
Well, once the saw got plugged in, it screamed across the bench heading for Stumpy's face. He reflexively put his hand up to save his face and whacked off three of his fingers before he could wrastle it under control.
