I've used both and the extended performance discs last a lot longer and cut faster. I think the extended performance discs are a lot more “grabby,” which for me makes it a bit more difficult to cut on a straight line and also causes a lot more kickbacks due to binding. The more expensive discs take a lot more abuse without cracking and if a small chunk of the wheel breaks off on the outer edge, I feel a lot more comfortable using the damaged wheel with the extended performance discs. Overall, they just feel like a much more solid quality cutting disc. When I use DeWalt cutting discs, I use the cheaper high performance cutting wheels most of the time, just because they're cheaper and it’s easier for me to cut straight with them. The more expensive discs cost almost twice as much and they certainly don't last almost twice as long.
I’d say buy a few of each and give them a try, then you’ll know for sure.
