Ok, my preliminary report. I had only played with Notion a 3 hours. This is what I find.
Sample Tank3 can't load samples in Notion5. A visit to presonus forum revealed that this is a windows only problem. The mac users are having a party ( just a figure of speech).
To add insult yo injury, the 32 bit version of Notion5 wouldn't load Miroslav Philharmonik vst.
So Notion5 and Ikmultimedia doesn't seem to work together at least for now. I can't use Miroslav Philharmonik either way.
Back to the Rewire topic, I had tried rewire notion5 into X3 and it works. First step that I missed initially was to enable rewire inside Notion first. The bundled sounds that came with Notion5 are quite good. However, I am not sure if there are different articulation available in the orchestra sounds.
Notion can send up to 32 channels of audio via rewire.
One interesting feature of Notion5 is the Ntempo. I can control it's playback tempo in realtime by tapping a qwerty keayboard. I can imagine playing piano live with a second person 'conducting' the midi orchestra.