Before you buy many smoothie vendors have equipment available as long as you buy their products. You may want to consider that route. As far as Vita-Mix vs. Blendtec, I like Blendtec Smoother, but it's 3 HP motor is a bit of over kill and it is not cheap. Eventually I picked Island Oasis as my vendor and they provided to me their R2 D2 looking blender. When it died, Island Oasis had me tried Hamilton Beach Tempest 91555 blender. It's a very impressive blender if you do up to two 16 oz smoothies at a time. For moderate volume, I think it is a good alternative.
You really need to try them side by side, but if you can't, go with the Blendtec as the Vitamix has a terrible vortex action. Blendtecs can be programmed to pulse first to break up the large chunks, and then mix the product to a smoothie consistancy. The Vitamix can't do either. Hamilton Beach is now made in China and the quality is not like the old USA made machines.