Heskiethprichard, I don't have a Leica 900, my brother inlaw does and I used it a little. It was hard to get ranges on trees out past 600 in bright sunlight. I tried out a LRF 1200 and it was hard to range trees in brigh sunlight past 800.
I currently have a nikon 800 and I have been told that the ranging ability is very simmilar between nikon and Leica (Leica has much better glass). I have a hard time ranging deer sized targest at 500 and beyond. Must be perfect conditions to range at 500. If you only want to range too 4-500 yards I think you would be OK w/ the Leica 900, but if you plan on ranging beyond you will be dissapointed. It takes a larger target, but not a reflective one. Look back on the optics a couple months back there was some good discussion on range finders by much more experienced people than me.
good luck, Mark.