I put EX wheels on my 2007 HCH. I put on a good all-weather tire(but heavy), the Goodyear Triple tread. The stock HCH wheel/tire combination weighs about 35 lbs. The EX/Goodyear combo weighed about 48lbs. It seemed to cost me about 5mpg. If I was going to do this again, I'd choose a lighter tire. But in retrospect, I think I'd leave the stock wheels and tires and just get the tires siped.
Oh, I bought my wheels on Ebay. $300 for 4, which was good, but be careful. The seller needed some coaxing to get him to send them.