Just my 2 cents worth as there has been a lot of good advice provided already
I think looking at the entire kit makes sense but you need to be comfortable with it and I do think it depends on what WWF means to you as there are a few different ways to have fun and different kit performs better for different styles. And I think there are compromises with most changes in gear.
For example,
Downwind carving powered up might have smaller faster foils and smaller boards
While Downwind wave riding with the sail flagged might go better with bigger foils and bigger boards but with tiny sails
I love all the different styles but prefer to take advantage of the reef waves that are about 90 degrees to the wind i get to ride in maui.
I am about 85kg and have a board about 110L that i ride strapless (not good enough to ride with straps) Its about 6ft long and 27 inches wide. I ride with freestyle sails 4.4 and 3.6 from about 15mph to 30 mph and a 3.0 free ride sail up to 40mph. I do have a 5.4 freestyle sail that I bring out when there are no white caps
I ride an SAB 808/325 combo on a custom 830 fuselage unless its too light then I will go to a 835 or even a 940. I should add that I have reduced the distance between the sail and foil by having a custom board made with a more aft mast track and a custom fuselage that moves the foil forward. I think it just loosens things up.
I also prefer a tuttle connection as I find it stiffer and my board shaper says it's a pound or 2 lighter. But I think sailing strapless allows me to avoid moving the foil around by moving my feet instead. Each to their own as tracks and straps have plenty of benefits as well.
I love to carve hard on the wave face, if I don't blow up, as I have a better chance of staying on the wave face with the tighter turning gear. So the smaller foil and and sails help me maximize the fun. The bigger board just lets me get going on the smaller foil and sail easier. I say bigger board but it only weighs 13lb so the swing weight is still pretty low. Hope this long answer helps.
If a picture is worth a 1000 words here you go