Which 27 inch double oven?
Have you considered Electrolux? It bakes very evenly, preheats in 7 minutes and compares very favorably with the oven in my Wolf range.
Have you seen the appliance forum on Gardenweb? It might be helpful to search those brands there.
It depends on what you want to do. I would in fact consider purchasing separates instead of a double. In my case I am doing a bosch oven and a separate convection microwave. I am also going with a Capital Culinarian gas range with gas oven.
The major difference you will find is finish and some of them will have the option of steam. If you are a baker go with one of the steam ovens.