Reef Octo makes great products, I voted for the bigger one(you can stock more).
The ASM's were great in their time but it's outdated technology when compared to the other skimmers. RO has a bubble plate ASM doesn't, RO has a conical body ASM doesn't, RO has a water level adjustment ASM doesn't, RO has much better pumps, venturies, and wheels ASM doesn't. I am not bashing ASM, just stating the features of the skimmers you are looking at.
I personally wouldn't even put the ASM in a list with the new Reef Octopus/MSX/SWC skimmers.