Pretty sure I know the response I’ll get but Im looking to see if there’s a difference for Olympic distance racing, I have three races coming up;
Dartford Bridge
Hamburg Wassummsomething
London Tri
They’re all flat I think but with lots of turnarounds, non-drafting
I’ve done both. Normally I’d say TT bike always.
The times I have used my road bike I hadn’t spent any time on the aero bars and just felt more confident on the roadie
TT no question
Dartford and London as you mention have long straights, albeit with some turns
If the Hamburg course is the same I did a TT should be fine, couple of dead turns but plenty of long stretches.
Only problem is lots of traffic going at different speeds.
Okay, I’ll swap over the bikes on the turbo this weekend.
Cheers lads 
TT at Dartford, slab of beer for the other two as you won’t be racing them 
Looked back at a couple of files from Dartford
Managed 23 mph average for the half distance even with all the dead turns/roundabouts
So TT bike all the way