On the wiki - then please take the time to flesh out/correct any details you find lacking. The articles don't write themselves, and I definitely agree that articles on wikis often do expect too much knowledge. It is extremely easy to update them, and don't be afraid or play down the value even of very simple edits. A few words here, a bit of punctuation there can do wonders for useability! If you have any concerns that your changes may not be correct, feel free to post them here first for review and discussion.
On the 2 NICs point, can you please point me to the article(s) that you feel imply or explicitly state that 2 NICs are an option. This needs to be eliminated immediately and I will take on that task.
On the evaluation and testing you want to do - yes, it is a little difficult technically and conceptually to get around the 2 NIC thing. This is probably the most common issue - "I just want to test, before converting my whole network." Unfortunately, the architecture is so tightly bound to this that it would be a major undertaking to try and provide a single NIC configuration out of the box. There has been a little progress on the web admin side that will probably appear in the new version, but realistically you are still in a 2 NIC scenario for your purposes.
I say conceptually, because most people initially see this as a huge imposition. In fact, if you read what I have been saying, it is really only in the mind that it feels that way. Buy a $10 NIC and $2 patch cable and you are set to go. The vast majority of home networks tend to be a broadband router also serving as a DHCP server, with a patch cable from it to a switch which the rest of the network hangs off.
Simply unpatch the cable from the router and plug it into the internal NIC, then with the new patch cable, patch from the external NIC back to the router. And you're done! The router now provides DHCP only to the hybrid LMCE, and LMCE provides DHCP to the rest of your house. Nothing else has to change, its that simple. When you are done testing, reverse the process and reboot your other equipment to get a DHCP lease off the router again. Complete.
The only issues you are likely to come across with this are 1) if your router has built in switch ports and you are using those instead of a real switch, then you need to get an actual switch - this doesn't sound a problem in your case. 2) whilst you are testing, your internet access in the house is dependant on the hybrid machine being up - generally this is a fairly minor inconvenience and only for the 2mins it takes to reboot occasionally. 3) if you are using a bridge broadband device with PPPoE dialer on a computer, then you need to go through a few extra hoops to get LMCE to do the dialup for you - I can't stand PPPoE, and really recommend using a proper router!