Finally made the trek and well worth it. The corned beef reuben was outstanding, probably the best I've had in town: juicy, flavorful, fall-apart tender. At $5.98 it makes Subway's/Quiznos' sandwich look like lukewarm consomme at a spinsterish teaparty.
I spotted the roast beef and decided to order that as well. While I was quite stuffed from the corned beef, I managed a few bites. The meat's of the same consistency as the corned beef (supersaturated with jus, collapsing under the weight of its own flavor), and judging by the irregular cut of the meat and the clumps of burnt fat and peppery rind, it looks handcarved. Not some presliced, processed lunchmeat "product." If you're not in the mood for corned beef, the roast beef is an excellent option.
So it looks like, for roast beef sandwiches, we've got most of DC's quadrants covered: when in NE, go to Deli City; when in SW, go to Atrium Cafe; and when in NW, go to Hodges. Any decent roast beef in Southeast?