The profile of this thing is going to make most of the difference. If the climb is as long as you seem to think... I dont see Jrs sticking together. If they do stick together its because they all are nervous about each other... but this late in the season... Im going to assume that the more solid JRs will know who each other are and set their hooks accordingly. If there is a guy in the front that everyone seems to just be sitting on... thats the guy to watch.
If the hill is long and or severe.... I see it gapping out, and someone getting away solo even though its only 16 miles. With the JR gearing, wrapping up on the downhill and remaining distance after the descent... Im going to think that it may be a bit more difficult to close a big gap. If the hill is early on, then it will come back together as I haven't found many Jrs that can TT all that well. If it is later on, those over the hill first will win... etc. So, position yourself accordingly.