CFL Foiler said..
Greg's wind range charts are accurate. Make your decision based on the chart for sure. If you think your typical wind range is going to be 15 with gusts to 20 I would vote for the 4.2. The 5.3 can be ridden in those conditions, its actually just sheet and go in those conditions, but you will be very lit and probably not ideal for learning. The 4.2 is much easier to manage size wise and they all can be pumped well which is similar to a wing.
I love my 5.3 though. Its awesome for 10-15 conditions. Its a rocket ship in 15-20, still fun but probably a bit much for learning. I am so happy with the wind range that I actually skipped a size and went with the 3.2 for my next size down.
Thanks! By the way, Greg has added a new range for light wind conditions:
boardridingmaui.com/pages/l1-parawing
