I agree with Hermes on the advantages to being on the big ring. It feels better, mentally, even if the ratios are equivalent. Part of it for me is that, racing here in AZ, if you drop off the big ring, chances are you are no longer racing. There are only a handful of climbs here which require anything lower than a 53-23, and being able to stay on top of that gearing lets you know you are in the right range to compete.

I've had a TT bike for a few weeks now, and I'd say I'm on the small ring only 1-2% of the time. I stay on the BR at stops, since it is so easy to drop onto the aerobars and get up to speed without using the SR or cross-chaining. Were I not swapping my PM crankset between the TT bike and my road bike, I'd put a 54 or 55 ring on the TT bike.