I just received a Vitamix 4500 as a gift, and couldn't be more thrilled. (I suppose it is only foodies that are able to receive kitchen appliances from significant others as gifts with positive results. Hehe.)
HOWEVER, reading threads on features and such has given me the inkling that I should send it back (before even opening) and upgrade to the 5000, which has variable speed control.
[Note to those that didn't know the wattage on the Vitamix models - its 1380(!) My dying Oster is 325.]
Thank you kindly!