That's exactly it. I found - through the 20 years that I'm windsurfing now - that I could manage to plane each time with smaller sails, the better I got. It doesn't mean that I don't like bigger sails. I also like to slalom with 5-6 m2 sails in 30 kots, but on FLAT water (typically lakes, or off-shore sea conditions). I find that in "heavy" wave on-shore conditions, you need a lot of control and this will be hard to achieve with too large sails and to large boards. In these "heavy" conditions, the technique to get planing with smaller sails gets more and more important. Once planing, you will feel much more comfortable, because you will need to be prepared for each wave, either to avoid it or to control the jump and flight in the air.