Couple of problems here:
1) You are passing attendee.attr() to your template which is just a plain object. Live binding can only happen if you are using Observable values (can.Observe, can.Observe.List or can.compute)
2) Even with the fix from #1, you need to use can.each or Observe.prototype.each to iterate over the Observe. This will live bind to the length of the Observe. You also need to access properties of an Observe using .attr() if you want live binding.
I've modified your fiddle with the 2 changes and now live binding works.
