The rain and zip modes are really not important. The units that have this (primarily bushnell) are just using a mathmetical algorithm (inside the chip) to try and guest what your really trying to get a reading on. The nikon uses a narrower beam so that thru aiming you get a true reading. I spent some time using the bushnells and if you want cheap they make a good unit. For bow hunting any unit will suffice as they all measure excellent at close range. If your trying to shoot thru the thich stuff up close the nikon will give a more accurate reading but if the laser has trouble hitting the target your arrow wont and the issue is moot.

It comes down to purpose. For archery 50, 100 or even 150 yards or less ranging every unit will do. If your a multi purpose hunter/shooter and need more range or ability to pick a target thru brush than you need to spend more.

I just brought my newest unit in and let some guys at work play. We hit a water tower at over 600 yards and a power line at 450 thru a screen window in my office. The cheaper units would even go thru the screen!