60D - Canon 17-85mm vs. Tamron 17-50mm VC ?

Hi!

I'm a student in photography and I just bought a Canon 60D kit that came with a 17-85mm and a 55-250mm lens. I like the latter but I've read quite bad reviews about the 17-85mm... I've done a lot of research online and found the Tamron 17-50mm VC. I'd really like to start using my 60D but can't touch the 17-85mm if I want to resell it... Would it be worth it if I wait and try to sell it new to buy the Tamron lens? I mean, as a semi-beginner in photography will I really notice the difference between the two lenses? I don't really have a lot of money left so I can't buy the 17-50mm and sell the 17-85mm later.

Thanks