Even though there’s more park time… to me it feels different. Now I’ve never run a DL half, so this is just based on speculation and You Tube videos. Bit because the park time is in the middle and end (slightly) at WDW…. There’s 5 miles of anticipation On those highways! It feels to me like it’d be awesome at the start and then rough once the park time is done- no different than my local Rock N Roll (which I havent done either hahaha).
FWIW- warm or cold… running in the rain CA has been getting the last few weeks would be miserable. It’s day after day of downpouring. Im not sure they could hold the races. DL doesn’t drain well. It would for sure be at your ankles in spots. I saw video of the Mission Beach boardwalk flooding what looked like 2-4 inches. Sewage is spilling up into the rivers. It’s rough….
They would have absolutely cancelled the races if they were being held this weekend. That amount of rain is not safe for large crowds to run in, especially at Disneyland which gets VERY slick in some spots due to the materials they use on the ground. It's not all nicely smooth slip free pavement like WDW is. There are cobblestones, pebbled concrete, etc. And like you said, Main Street is prone to flooding to such an extent that ducks have been known to SWIM down it.