I was selected for HOBY and went my sophomore year. The only thing I learned from it were some irritating cheers we were forced to do at periodic intervals (if you go, you'll understand what I mean--and you'll hate the word "outstanding", too), and I'm fairly certain a couple of the speakers we had were pretty much frauds. Did it suck? Yeah. However, ultimately, I lost a weekend but probably got some points on my application. With appointments getting more and more competitive, you don't want to pass up an opportunity like this. Like kinnem said, you have nothing to lose by going. And who knows? It might make the difference between getting a BFE and getting a TWE in a couple years.
Also, the fact that you were selected for HOBY is, in and of itself, a positive sign. Keep up that leadership and you'll be in great shape when it comes to apply!