Apple's (AAPL) iPad Mini will increase the company's overall tablet sales, but will cause some potential buyers of Apple's higher priced, regular iPads to buy the cheaper, smaller tablet instead. In a research note Wednesday, Janney Capital Markets analyst Bill Choi said he expects 15% cannibalization to current iPad sales from the iPad Mini. Piper Jaffray analyst Gene Munster puts the cannibalization rate at 20%. "We view the smaller iPad as