Hmm... my experiences were the contary of artorscience, so perhaps it depends on what department you're in. I personally found Erasmus a piece of cake to get onto, if you wanted to go you could go and it wasn't awfully competitive, whereas the international exchanges (ie: non erasmus) were more competitive. The international one took more consideration into your exam results from 1st year and said you needed a high B average (65%) to really be sure of being considered for a place, whereas the erasmus people didn't say anything like that. The system works that you apply stating your location preferences, then you write a PS type thing too. Then they rank everyone according to grades from first year plus a bit extra if you had a good PS/will be a good ambassador for the university, then they just go down the list allocating everyone their choices in order of preference until there are no spaces left.
If you can, I would personally stick to erasmus. The exchange experience will be amazing whereever you go, and if money is at all a concern to you, then erasmus is where its at. If you pay tution fees the EU will pay them for that year, and you get a non repayable non assessed grant of around 280 euros a month from the EU on top of your normal student loan. If you do not study in the EU you have to fund everything yourself.
Certainly stick to your guns and apply for it in 2nd year, I was doubting myself even though this was something that I'd wanted to do for years. But I went in the end, and got back home 2 weeks ago - I've had the best year of my life.