The roller will crack the paint too.  Unless you've got the time to get a heat gun and go *very* slowly, you will crack the paint on the inside of the fender for sure, and possibly the outside lip as well. 
 
I spent like an hour per fender w/ a heat gun on my car and still had to touch up the inside of the lip to prevent rust.  But at least I didn't crack any visible paint.
		 
		
		
		
		
		
		
			
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