The problem with the pressure switch is that you have to continue to hold it down, if you shift your grip or lighten the pressure the light will go out. The toggle switch works much better in that situation. I had a pressure switch on the light on my 45/70 that was quickly replaced with a push putton on/off switch.
My experience with weapon lights is strictly limited to law enforcement use. I preferred the pressure switch or a rocker switch that was spring loaded so you could turn the light off when you didn't want the bad guy to see you. I can see that with bears it is probably not a big deal.
I doubt it is legal here in AZ but have never contemplated it