Ours was iteration. We always knew we wanted to be a tunnel robot so we could do everything. Our problem was one of packaging. Having a compact assembly that fit inside the robot then allowed us to hang was difficult. We went through probably 4 different designs before we were happy with one of them.
At the end of this video you'll see a nice shot of us hanging simultaneously with Bees (at State Champs) and Rush doing the same with their hanger but running out of time.
Our system required a bit of finesse to latch on, and we were rarely as bad at latching as we were in this video. Chalk it up to first round jitters on the part of our driver
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You can see where the "slam into the bar" here saved time for the bees - it took us probably 2-4 seconds longer to get locked on. Unfortunately, we also made our robot too rear-end heavy. You can see the result as we're a second or two slower to get up than they are.
In the end, as someone else said - once we had it down to hanging in under 8 seconds, we decided it wasn't worth it to keep going. We had thought about connecting it up to our drive train, but simply didn't have the "drive" (pardon the pun) to get it done in time for Atlanta.
http://www.youtube.com/watch?v=ExWcNU97FnY