There are a number of suggested ways to bake a large cake.
I baked for 25 years using nothing. I greased-only-no-flour'd my pans and they did just fine. I discovered baking strips about 5 years ago and I wont' bake a cake without them now. They reduce (not eliminate, but REDUCE) the doming of a cake. Metal is a conductor of heat, so naturally the edges of the cake (that is next to the hot metal pan) cook faster than the center of the cake. The wet baking strips cool the edge of the cake pan, so the batter bakes evenly and uniformly.
Some use the heating core with good results. Some use one or two upside-down-flower-nails in the pan. what these do is help conduct the heat to the center of the batter so it cooks evenly; helps avoid the result of overcooked edges and underdone centers.
I just turn the temp down and bake at about 300. Bigger layers I also like in a gas rather than an electric oven, if you have the option. I've never used a heatng core and don't plan to start. I have used the bake even strips, but I wasn't as impressed as Indy is.
Looks like we all have our own method! I bake at 325, homemade pan grease/parchment, 3 rose nails, no bake even strips. 
Yes I used to have problems too getting the middle part too cook all the way - all i did was turn the oven down 25 degrees and problem solved. I don't used any heating cores though.
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