<image> Store A and Store B are running promotional events for the same product, with the following reward schemes for customers who purchase the item: 
Store A: Customers spin the shown disk, and if the pointer lands on the shaded sectors (both shaded sectors in the image are sectors with a central angle of $$ \dfrac {π}{4}$$, with boundaries negligible), the customer wins.
Store B: From a box containing $$2$$ white balls, $$2$$ blue balls, and $$2$$ red balls, the customer draws out 1 ball (all balls are identical except for the color); the probability of it being a red ball is $$ \dfrac {1}{3} $$. If the customer draws out 2 balls at once, and the balls drawn are of the same color, then it is a win.

(I) Calculate the value of the real number $$a$$;
(II) Question: In which store does a customer have a greater chance of winning when purchasing the product? Please explain the reason.