"Doomed" is too strong a word, but Sloan's Round 2 is harder than Round 1 simply because they only have 2 rounds and the majority of their admits come from the Round 1 pool.
If you feel you're a competitive candidate for Sloan (i.e. you don't think your resume is weaker than the kinds of people you know going to Sloan or other comparable schools like Chicago, Kellogg, Columbia, Tuck), then just go for it.
Alex Chu
alex@mbaapply.com
www.mbaapply.com
http://mbaapply.blogspot.com