As a precedent for this post, I am using the most recent beta of Mac OS X 10.9 (13A558). It is pretty much done and to be released in Early September. I know that can always be the issue at hand, but just wanted to rule out anything that may be happening that isn't beta-related.
I've downloaded the Pro version yesterday, and everything works fine over the regular Wifi Network, except with a lot inconsistent latency issues, controlling Reason 6.5.
As recommended, I've established several "ad hoc" or computer-to-computer networks with different variations on the same theme. (changing settings such as Channel, trying differing IP addressing schemes, Static IPs, DHCP mode ect. all with the same result.
Every time I connect MIDI Designer to my new network, it will seem to sync fine on the iPod Touch and then it disconnects after about 5-10 seconds. I haven't had it connect for any longer than that.
On the Mac, in Audio MIDI Setup, when double clicking the Network Icon to bring up the options, before allowing me to continue my setup, I do get this error message. With 0.0.0.0 for the IP address for some reason:

Then, I can setup everything as recommended. My iPod Touch shows up in the Directory section like normal. Then I can "supposedly" connect my device - in the Audio MIDI Network dialog window only. I cannot get the device to connect by selecting the network in MIDI Designer. Even when I select the network in MIDI Designer, it doesn't show that it has been connected in Audio MIDI Setup. And with in 5-10 seconds, MIDI Designer "disconnects" from the network. But, I'm not sure if it is really ever actually establishing a connection at all, or just attempting to and timing out.
Below is my Network setup dialog. I clicked connect in this dialog to get my device to show up on the right under Participants, otherwise, it will not. It will NOT show up if I attempt to connect from MIDI Designer. (As shown in the tutorial video).

Also on occasion after attempting a setup, when closing the Network dialog in Audio MIDI Settings, I will get this version of the same warning as I showed at the top, but WITH the IP address I put in this time. (the screenshot below was from a different session than the screenshot of the Network dialog above. That's why those two IP's don't match.)

I have been at it for a while now and narrowed it down to these issues. Like I said, It does work when wirelessly networked over my normal Wifi connection I use for internet access and local networking. I've turned File Sharing on and off. And no other sharing services are enabled. I can't even get to the point to see if MIDI Monitor will show anything. Which it does when networked over the regular Wifi. I do realize that networking can be a complicated issue, so I've tried everything I could think of and research.
I would try to use BlueMIDI, but unfortunately my iMac's built-in Bluetooth adapter isn't new enough and unsupported.
I have followed the steps outlined in the tutorial video step by step. And then tried lots of troubleshooting options from there.
I love this app. It's definitely one of my favorite tools to be able to set-up a rig for pretty much anything. I'd just like it to be feasible for use- without much latency. Any changes or suggestions to get it working within an "Ad Hoc" network?
Thanks, Jason.
Computer and iOS device used:
iMac 27-inch, Mid 2011, iPod Touch 5th generation.