I think i'm nice inbetween weight between you and your dad. 115kg.
I usually ride a 132x41 twintip (3E royal (doesnt excist anymore) (its a direct cousin of the Fluid Grind and twoseven) its defenitly one of the nicer boards i have ever ridden. Its smooth and gives me alot of float and simply goes upwind FAST.
Last time i was in OBX Dimitri got me on the Epic Droid and Oxygen. The Droid 135x41 was really nice it did give me a little less float then my own board but the riding was nice i think because of the small rocker the board planed even easier. The board really suprised me its more playfull then i imagined and gives a good edgecontrol.
The Oxygen well in lightwind i think its a great board. But as soon as the wind becomes stronger i found it a more difficult board because of how wide it is. Maybe its something you get used to.
If you ride mostley in OBX why dont you ask Dimitri to lend you 2 testboards? You can see for yourself. (and ask him about the NEW board
For your dad the Oxygen might be fun to learn on. i think that board will give him the extra float to easy learn the waterstart and first riding. For when he is a descent rider i think he will like something less wide. But to learn its definitly good.