Cruising in sub-planning conditions is fun. Mostly relaxing, especially if you are using a harness. As you get more comfortable you tend to push for more speed and begin to grab the larger sails. Here is the bottom line- even if you are still happy cruising on an old long board you should consider getting your own larger rig. You would be amazed what a 6.5 would do for your summer light wind days- and when the 6.5 seems to not be so powerful the 7.5 to 9.0 doesn't seem so bad! I put my old 9.5 on my very old mistral superlight in about 4-8 mph and had a blast. Just hook in with the harness, lean back and proceed to cruise 'till sunset.
I've learned quite a bit about planing/sub-planing in light air this summer. AND when the wind is 0 mph or less paddling a board or kayak. We do have some fun boards in the container at Belews but if you really want to start having fun have a look around for some second hand larger rigs. Heck if anyone is interested we could start talking formula type stuff for light air planing. I can promise you being locked in and planing without a white cap or swell in sight is tons of fun- and that certainly is the case quite frequently on Belews. I love my 9.5