What are the pro's and con's for each of these stones? Can a quadrillion be used as a center stone? Is it considered valuable? Is light leakage a problem in radiant cuts? Is there a greater chance of catching a corner of a princess cut on something? I am looking at both princess and radiant (my jeweler seems to favor the princess - why?)I am soooo close to purchasing and would really like some honest opinions, real life opinions, not "look at the depth , look at the table", etc... just some good old fashioned pro and con comparisons.