Just buy it. You won't regret it. I have the 52 and its my go to mower. I plan to get a 36 vride to replace my 36 Viking. This is my first scag and I love the vride. Beats sitting down without a doubt. Also, top speed is not something anybody in this business should be making buying decisions on. If you cut lawns at 10 mph or faster, it will look like crap and you are doing low quality work in most conditions. Just my .02
The 52 vride top speed is 8.5 mph. I don't go that fast unless I'm headed towards the trailer to load up or cross a property while blades are disengaged. I probably cut in the 5 to 6 range for best quality of cut.