It always bothers me when someone asks this question. Should I wait for the next one? If you have to ask, then you should. However, realize that there will always be something better coming down the pike in just a few months.
As far as is having an ipad mini, and an ipad redundant? I would say a bit.
I use my mini in the car, plane, or sitting on the couch. I use my ipad for work. Typing proposals to customers, entering orders, emailing pictures etc...
Could I get by with just one or the other? probably, but I am glad I do not have to.