I would personally choose the Dornbluth.
They are terrific people all around- extremely nice to deal with, and don't worry about service issues, since the movement is based on a widely available movement, if you for some reason don't have the funds to send it directly to them, any respectable watch repair will have the new mainspring for it.
Also, I'm a VERY big fan of the large central seconds! Seeing a huge seconds moving around the dial makes time appear as if it was moving slower. The regulartor dials have that effect for me in general.
However, are you ready to wind the watch ever day?
I would go for the Dornbluth hands down... if you change your mind in a year or two, you can easily pick up an IWC anywhere. but the experience you'll have purchasing the Dornbluth, etc. will probably make the watch a keeper for you.
You have some great decision making ahead for you!! Congrats!
S