I currently play with the OS and my second choice was the 100. I chose the OS because it did everything the 100 did, but felt better overall to me. I had used the OS for 17 years before coming back to it so that may have had a lot to do with it.
Since I was already used to the maneuverability of the OS it wasn't an issue for me, but I can see why players would prefer the 100 as far as that goes.
The sweetspot of the OS is larger, but not by a large amount.
I find the power levels to be similar, but the OS definitely has more.
Serves weren't much difference for me either, but I thought the 100 had a little more control.
The only thing that I have encountered that I find a little troublesome is the string life of the OS. Both sticks ate up strings for me, but the OS is tough to live with sometimes.
For example, I played a match this weekend with a fresh set of multi and broke it dead center about three games into the second set. I prefer multis in these sticks, but it's cost a small fortune already. I'm trying some low tension polys, but still prefer the multis performance. My Kevlar setup lasts two weeks, but I have to work much harder to win points.
I'm at a conundrum. I'm going to commit to using the ELT poly the rest of the week, but my game suffers with it so far.