Actually, it's mostly marketing segmentation. Even the very old WRT54G is capable of loopback, so I don't think the hardware is the issue. The newer consumer-grade routers most certainly have this loopback feature disabled merely to avoid enterprise users from opting for these "cheaper" models. Sure, you can hack them if you are an end-user, but enterprise users wouldn't. So, yes, E2000 + DDWRT will enable loopback. But then again, so will almost any Linksys router and many other routers from other companies. Well, what's most important is actual performance. The internal antenna actually works pretty well. It doesn't necessarily mean external antennas are better. Some people just prefer it because they want to swap the original antennas for high-gain antennas.