I have a bike with red and a bike with ultegra. Both do their jobs. It really comes down to preference. After riding both, I greatly prefer the red. I like the double tap, zero loss of the red, and (most importantly) I just feel more comfortable on the red.
I will actually be selling the bike with ultegra on it soon, and building up another bike with red.
See if the shop will let you take both for a ride (or at least put them on the trainer) and just ride them. It won't take long to see which you prefer and are more comfortable with.