Sorry for the 41ish flavor - but it isn't...
For collegiate racing/training team bikes should I buy 105 at 60% the cost of Ultegra? I think so.
I have little experience outside the Dura-Ace stuff, and that is price prohibitive.

I am getting the USAFA team some parts to build out 5 bikes (alloy frames) for racing. These are team loaner bikes. Most of these racers will be starting racers, but think fit 17-22 year olds training 10 hours/week and racing.
Bikes will weight ~17lbs. Most will be used as collegiate C and some B races.

Then for me - off topic - definitely 41 stuff, but feel free to toss in an opinion:
A non-racer - strong, heavy guy that likes precision. I'm leaning Ultegra for me.