I've had the Leica CRF 1200 for a while and I loved its compact size and light weight and the optics are excellent. However I found it didn't quite have enough range for me.
Up to 600m the CRF 1200 could range pretty much anything in any circumstance - well except in thick fog!
Between 600m and 800m it could struggle with say a black object on a very bright sunny day. Repeat readings often needed before getting a successful one.
Beyond 800m it struggled and in the wrong conditions required more patience to get a reading than I personally possess! Usually I'd give up! Worked much better in low light - ranging up to 1100m with some problems but manageable.
With the new Leica CRF 1600 I can easily range up to 800m first time without problems in most circumstances. Bright sunshine? No problem!
800m - 1200m the CRF 1600 can range pretty well even in bright sunshine - which always seemed to cause problems for the CRF 1200. May take a couple of attempts depending on the object and something more challenging things may not range - for example a small sparsely leafed tree in direct sun.
Beyond 1200m depends on the conditions and the object. I can obtain a reading - after a few attempts - in direct bright sun but very hit and miss depending on the object - more misses than hits.
In low light - dawn or dusk or a very overcast dull day - the CRF 1600 can range amazing distances. I managed ranging a house at 1878m without too many attempts. The best I ever manage...