In terms of rangefinders, they generally have more problems in bright sun, as Burns stated. Overcast is actually better lighting conditions for a LRF. Fog obviously creates problems for laser rangefinders.
In my experience, any of the popular LRF units can have alignment or source-receiver issues. I had a Swaro that would range to 1800+ with ease, one handed. If you listen to some, they say that Swaro sucks. This is just ignorance to the actual root cause of the issue with their LRF. However, people are quick to state their assumptions based on limited knowledge, and limited samples.
I also had a Leica 1600 that wouldn't range across a small meadow. The replacement Leica easily beats two Sig Kilos on difficult targets. One Kilo was replaced by Sig, as it wouldn't range well.
If you have a LRF with poor performance, but solid reputation, then I'd see if you can get it inspected and replaced under warranty.
