Tricky call to make about whether tri-bars are the way to go in a 4-up on a technical/rolling course.
Certainly in a solo TT, a TT specific bike will always be faster than a road bike if it puts the rider in a good aero position and doesn't compromise their power output. Even on a rolling course most of the time is spent at 20mph+ where aerodynamics count for more than weight saving.
But, just sticking tri-bars on a road bike can sometimes make things worse not better; it will bring your arms closer in so they don't catch the wind, but it can also raise your shoulders and actually increase frontal area. It all depends on the rider and their position, bar height & reach etc.
The other thing to consider in a team TT is that for a large chunk of the time you will be sitting on a wheel (this is where Ajay starts paying attention), so will be sheltered anyway. Plus if you're not used to riding on tri-bars it may be safer to stay on the drops/hoods where you have more control.