Agree with the comments on humidity acclimation and prep - I ran the Dopey Castaway Rebel Coast-to-Coast Challenge last month and definitely found humidity a factor in my "normal" pace even with the prep - for example, I ran the WDW Half in 2:10:55 and a week later (after WDW Full/Dopey, two Castaway 5Ks (Cay Challenge and normal one right after) and DLR Star Wars 10K) I did the DLR Stars Wars Half in 1:58:52...almost a minute/mile faster in the lower humidity.
Humidity aside, I will be very interested to compare the DLR Rebel Challenge entertainment (Jedi Mickey, Princess Minnie, Ewok Chip and Dale, Darth Goofy, Stormtrooper Donald, 501st group, Star Wars specific mile markers, marching bands playing Star Wars on course, Star Wars music throughout DLR/CA, On course characters with scene backdrops including R2D2/C3PO, BB-8, Chewy, Boba Fett, First Order Troopers, Star Wars Rebels: Ezra and Sabine, Trash Compactor scene, Wampa Ice Cave, etc) to the WDW Dark Side Challenge to see which is better - perhaps WDW will have all the Star Wars Weekends backdrops and props out - regardless, it's all about the Kessel Bling which I'll complete in around 10 parsecs
Until we see the official course announcement, the description leads me to believe it is a reverse W&D course starting at EPCOT, then Hollywood Studios, Animal Kingdom and finishing at ESPN.
Any thoughts on the WDW Dark Side entertainment and course?