Will turning down Goldman hurt me in the future if i want to apply again?

Yeah, I can't give you concrete advice about reneging. Obviously, you've read the two schools of thought on this site -- some people think it's no big deal, others think it's incredibly risky and can screw you out of both offers.

I can imagine what you're feeling -- you went with your gut and you're wondering if you made a mistake. You're gonna feel weird about it for a while, but once you start working for another great bank (and those other banks are all great) and you like the people, I really think the odds are you're not going to feel the regret. You're going to have the same job, making the same (most likely better) money and you're most likely going to be able to have the same career/get to the same place as you would at Goldman. Are your chances better at getting to a PE megafund from Goldman? Maybe. But look at the chart somebody recently posted -- if you want those funds (and many people have written on this site how shitty the culture is at those jobs), you still have a good shot if you work at a dozen other firms. 

Just don't lose perspective -- if you work at any BB/EB/MM firm in IB, it's a fantastic job that's going to give you fantastic pay, experience and exits.

Just don't take reneging too lightly -- I really have no idea how often it works out with no collateral damage, just don't screw yourself out of a great job.