I have no experience with the oracle, however I have the dual boiler.
As others have said alot of this depends on what you want for a machine - certainly the grinder is the weak part of the oracle, and will limit you far more the machine will. I picked up my DB for £600 before xmas, paired with with a niche and make excellent coffee for £1100 - if anything with this set up its a little to easy to make coffee, not a bad thing of course, but will be even easier with the oracle, and anyone can use it once set up.
Will certainly make better coffee than most high street coffee shops (Costa, starbuck, nero etc) although with a gaggia classic and super jolly you will get that for 3-400.
I will be sticking with the DB for now, until the missus wants something new so I can buy a L1!