The Withalacoochie Trail is excellent. A couple of groups have organized centuries on it. It makes for a superb century with good support.
The wind is never much of a deal on the trail because it tends to have trees on either side that serve as wind breaks. Plus, the trail runs north and south and usually our winds are from the east or west but not always.
I am just a recreational biker trying to stay healthy. I did the 100 miles yesterday and achieved 19.5 MPH average as measured by my Cateye Astrale 8 computer. As you know there are many intersections. I did not count them but there are about 40 each way. I did notice that these intersections lower my average.
The Wind.
A gusty wind with 15 to 25 MPH will slow you down. Yes there are trees and they help but there are open exposed undulating hills like by I-75. It was difficult to maintain that 19.5 MPH average at times.
Doing a round trip will average things out but not quite. I get a higher average with light wind as opposed to gusty strong wind regardless where the wind blows from.
I also noticed a few aggressive bikers doing 25 MPH regardless of conditions. I can not do that or I will blow a fuse. My HR is up to 150 as it is. This is about my maximum.