If you have accounts at pretty much every book and live in Vegas you gotta use DB.
DB has every Vegas book except Cantor.
SO missing some.
DB has a few more offshores than SO also.
Quite a few books on SO are delayed.
Both are easy to use and have about a million things I don't even know how to use but it all comes down to amount of outs and live feeds and DB is superior in that aspect.