I have a 84 twin in my quiver as my high wind board.
I say high wind as I weigh in at 93 kg.
Are you after an all in 1 board or do you have other boards as part of your quiver ?
Where are you based and what beaches will you mainly be using it at ?
Can you get a test ride/demo on either or preferably both at the same time ?
Having just got back from xmas break where I took a single fin (light wind board) I got out on the twin fin last week and you couldn't wipe the smile from my dial.
IMO the twin fin simply allows you to get into places on the wave you couldn't or can't easily do on a single. Your wave count and enjoyment factor goes up exponentially

Kev