If only one seat were added, there would be an even number of seats in the House which would create the possibility of deadlock due to tie votes.
I would support ceding the residential areas back to Maryland and allowing them to vote in Maryland for a House seat and Maryland's two Senate seates but only if the 23rd amendemnt were simultaneously repealed. DC is not a state, nor is it part of a state, and the US Constitution is very clear that only states have representation in Congress.
UT was just short in 2000. But it’s likely that a Dem state will be just short in 2010. You’re not getting much (2008 at the earliest, maybe only 2010). It strikes me as a bad deal politically and then a constitutional violation as well.