I don't own and have never looked through the current Zeiss HD 5-25. I do, however, own two Zeiss Conquest scopes. One has the RZ 800 and the other has the RZ 1000. The reticle marks on the RZ 1000 are definitely thinner than those on the RZ 800.
IMO, the RZ 1000 is totally unsuited to low light use. That could be critical on a hunting rifle. Another thing to consider is that the RZ 1000 reticle is specifically designed for the .308 Win shooting 175g Sierra Matchkings. Unless you are shooting something with a similar bc and velocity, the RZ 1000 is not particularly useful.
I have a .375 H&H load that looks to be an almost perfect match and I intend to experiment with it some.
If you are shooting something fast, flat, and/or with a high bc, the RZ 800 is a better choice.