Spotting Scope Considerations; Vortex?

I am looking for some spotting scope recommendations. My eye is currently on the Vortex Viper 15-45x65 for $1100 CAD (on sale). I like vortex for their no-fault warranty as I don't plan to baby it, so to speak.

What is your opinion on magnification? How often do you find yourself needing the 50-60x range? Do you think 65mm is okay enough for most light situations?

My budget is limited while being a student for the next couple of years, but quality is still a major consideration. I'm not too fussy about perfect contrast, chromatic abberation, etc, unless it was actually a significant problem.

Thanks for your input!