To be honest, If the fire brigade have inspected the wheel well and told you that there is no fire, as long as there are no signs of fire in the cabin (smoke, flames, heat) then I would treat it as a false alarm and taxy to stand with the fire brigade following close by.
If there was any sign of fire I would evacuate and trust that the fire brigade will cope with people on the ground. Since the engines will be shut down there is no danger from them, and I'm sure a member of the fire brigade or airport authority will guide people to safety. Have you seen the Air Crash Investigation on the DC9 (may have been a MD80 or similar) that caught fire? It was engulfed in a matter of seconds so if there was any signs of a fire I would want people off straight away.
SW