I am not sure about the difference between TI BA II plus and the professional, but I have a TI Professional. I love it.. very easy to use and calculates very fast. I also have a HP12C. it is very hard to use IMO... I could never get used to the button lay out and input method...esp the NPV, TI displays Cash flows as C01,C02, C03 et(. very helpful when you are inputing mutilple cash flows) where as HP doesnt. I also think HP takes much longer in calculation than TI. IF any one is looking to buy a financial calculator I would suggest TI BA II+pro.
GL
Buzz