Sure, I'll respond.
The best way for Range E is laser range finder and is the preferred way. More and more sniper teams in the line units are getting them. (if they all don't already have them). That being said, the way a LRF is most effectively used is when a team gets into their FFP (hide) and draws a range card. They use the LRF to range preexisting objects on the range card. The intersection, the building, the bomb crater, etc. Then their use of the LRF is generally done. When a enemy soldier appears, they generally will have a reference point. "Subject, 15 meters to the left of the bomb crater, range 5+3, left 3." "Roger, identified"... click click click. "uuuuuuuugggggghhhhhhh"... "send it". **Crack**.
Now, if the mission entails an unplanned engagement (over watch, or "sniper up", etc) when you do not have a filled out range card, then either a quick mil-dot calculation or LRF is done to engage the target. Either way, the LRF shoots for about a second. Thats it. Its not like the laser is continuously on, and if you so happen to have the right kind of NOD's to detect and see the laser, you MUST be looking for it in the proper conditions and looking in the proper location just to see the quick blip. So far, LRF detection has not been a concern. That "may" change, but so will the LRF's. Remember, LRF's are used on tanks and many other things without worry of detection.