It is better with AWE disabled, not sure if Ultra RAMDisk was using AWE too. Hopefully these will be useful to someone
This is mostly for information purposes. See the attached benchmark - left is dynamic ImDisk, right is dynamic Ultra RAMDisk. I also attach the results for my SSD. There are some serious performance issues that overall make it almost worse than my SSD. However, I tried Ultra RAMDisk for an hour and it caused a BSOD during heavy read-write workload... so yes I'm forced to stay with ImDisk...