Aerobars are great downhill, uphill (as long as its not too steep) and of course on the flats...

The problem for me comes when you come to a corner when going downhill on the aerobars... no brakes and little ability to steer because of the change in your centre of gravity and hand position.

I tend to resort to the drops (I TT on a road race bike with aerobars - I have yet to get a TT specific bike) on downhills in a TT, I can still get very aero while having access to the brakes and more steering control on the corners.

My partner says to think of steering on aero bars as if you were riding a motorbike - that is rather than steering around corners, you lean your way around corners.

Me though... I stay on the aeros for as much of a TT as I can - but when I head down hill round corners, I go back to the drops. Your centre of gravity tends to be lower on the drops, and your weight distribution is different so it is a matter of getting used to the different position as much as the different way of steering.

Also remember while you are getting used aeros that in a cross wind, forget trying to use them... even experieced "seasoned atheletes" will tend to leave their aeros alone when there is a gusty cross wind.