Okay, so Surefire X400 has white light and it has a laser correct?  To what distance is that laser any good out to in daylight and then night time?  The X400 can be put on a rifle and then used with a tape switch, yes?  Is there a 'double pad' tape switch available - one for activating white light and the other for activating the laser?

I have one, there is a switch on the light to have laser only, light only or both. The tape switch is constant on or momentary .... based on your switch selection on the light. So no, you can't control what comes on with the tape switch. Can't answer your daylight question but its a red laser so I imagine its very hard to see in the daylight. I tried it once at the range at 50 yards on a overcast day. I could see it but very, very faintly.