I am 72 kg and have the 2013 iSonic 110. I sail it with a Simmer SCR 7.8 in flatt water and chopp form 10 to 18 knots of wind. I have no problems with the width. The board is superb for my weight. Normally I use a 41cm z-fin but if the wind is in the upper range and I want to go for GPS top speeds I use a 38cm. If I am tired and the wind is ok I can also use the 38 for more comfort.
My next board is a 92/63cm wide freestyle and a 18cm fin. With my 5.2 I have the perfect board to go to from the 110 in 16-18 knots. Sometimes in those conditions I can have both set ups on the beach and change between them and both work brilliantly.