So obviously the Zeiss is going to be far superior to the diamondbacks but I personally don’t think they will replace a spotter all together, especially in Montana.
I would consider maybe saving an extra $200 and keeping the spotter and buying used or even attempting to find a good deal on a better used 65 spotter too.
Based on your assumed budget of $1000 I bet you can get real close to upgraded glass on both if you buy used. I bought a new razor 65 spotter on eBay a few months back for $580 shipped. Love it. Can get used Zeiss or something similar (Nikon HG, Razor HD, Meostar ) for $700 range.
I guess really just depends on how you hunt and which glass you plan to use more. If you can do without a spotter for your hunting Zeiss will be better than vortex.
Just my 2 cents.