Lots of information and opinions on snipershide.com.
Here's one since all your choices are Leupold:
Re: Spotting scope options for 300 yard shooting
The reticle is the tough part, because it limits your options. I've peeped through almost every scope on the market. I'm not a fan of Vortex but out to 200 yards I can see a .22 hole with one. I know this because I owned a 60x Vortex. I've had Bushnells, Bausch & Lombs (junk), Vortex, Leupold mark 40x. I'm now using a 75x Nikon Fieldscope. It wasn't my first choice but it was the best that I could afford. I paid around 1700.00 new for the Nikon and I can just barely can see a 6.5mm hole out to 500 yards on a cold crisp day. I can easily see a .22 hole at 300 yards on all but the warmest days. There is such a huge difference in spotting scopes once you breach that $2000.00 barrier. Side by side at the same magnification my Nikon and Bushnell are worlds apart. It's literally a Kia to Mercedes difference. Once you get into the Zeiss and Leica you are at the Ferrari level, but your going to pay over $3000.00 for the clarity and brightness their fluoride scopes provide. My favorite scope is the Kowa brand. Their high line I think is best in the world. Recently however I looked through a moderately priced Celestron and was really impressed by the picture. It was good really good. I hate to say it but it was close with my 3 times the price Nikon. With spotters clarity and brightness are the key ingredients in my opinion.
To touch on the Leupold. I only use Leupold scopes. I do believe they make the finest rifle scope in the world. I have 6 Leupold's and they're all fixed power scopes. That being said I didn't like the spotter. I had the Mark 4. It had a large field of view, was compact and it's made in America. I'm sure reasons taken into account when our military chose them for observation. On the firing line however, for benchrest they just don't have enough magnification. The Mark4 is bright, has a large field of view, and excels at picking up bullet wake. It's excellent for what it's designed for. I have a fixed power 45x Leupold competition scope that in my opinion can see better than any spotter at any magnification priced under $12-1300.00.