Will it make much of a difference with regard to lines for attractions? We will be visiting/shopping World Showcase but not be drinking around the world
I would also stick with Thursday. It's crazy how much of a different experience EPCOT is when you get to saunter around the world at your leisure without fighting the sea of humanity. This park can range from amazing to stressful.
I agree with everyone else on going with Thursday. It's night and day how different Epcot is when the locals come during the weekend. The park is a madhouse on friday nights when locals are off work, just like Disney Springs. My parents are APs that live an hour from WDW and they go to Epcot on friday nights often, as do a lot of APs.