Thank you Sonny,
you beat me to it but I came up with the same figures.
According to the Princess brochure for Europe for '07 the mini-suites in all catagories are all the same size, 323 sq. ft. INCLUDING the balcony. The web site points out that the handicap-equipped mini-suites go up to 536 sq. ft..
Also, the price for a catagory AC mini-suite is listed on the web site as $4145, still considerably less than the $5388.95 for The Brilliance of the Seas.
At this point I would go back to what Sonny originally said: "It's a no-brainer"!!