Brett, the Digital Gateway licensing opens up all the ports on it. You can connect to any of the 76 possible digital ports and the 4 analog station ports. This license has very little to do with the user licenses. Those 8 you quote are good for licensing any 8 users you want. They can be digital sets, IP or analog but the UCX will only allow you to have 8 working, registered devices. As an example, if you wanted to connect 8 digital sets, you could physically connect them to any digital port on your DG and once registered they would all work.
With the DG license, the expansion ports are enabled which allow you to connect up to 2 DSM32 modules and you can connect to any of them....but only 8. If you want more phones working, you have to buy more user licenses, They come as single or bundles of 5, 10, 20 and 50 but you can also get a bundle that takes you from the 8 up to 25.
Give me a call and I will go over the licensing with you. Emetro was pretty light on that subject last week.