I have the two-speed (found a good deal on a re-manufactured one years ago through Amazon) and it makes awesome smoothies (we use greens and vegetables in addition to fruit). We also use it for soups, hummus, tahini, pesto, and nut butter, among other things. I have a kid with a wheat allergy and we've had great luck using it to make oat flour, chickpea and fava bean flour, buckwheat flour, and quinoa flour. I didn't shop around much when I bought it because this was what I could afford, but it's been fantastic. I'm not much one for expensive kitchen gear, but I love this and use it daily. Enjoy!

I found a good tool to compare all of the different Vitamix models here - http://blenderreviews.us/compare-blenders/

Yep, that's correct. The 4500 became the TurboBlend 2-speed. Same blender, different name.

http://www.beyondblenders.com/vitamix-turboblend-2-speed/

I'm thinking it's actually the same thing, but Vitamix renamed the product- could that be correct?

the Vitamix Turboblend 4500 Countertop Blender with 2+ HP Motor and

the Vitamix TurboBlend Two Speed?

My main interest is in green smoothies with kale and other "juices" that seem to burn out other blenders...