I've seen Matt Bottril uses them a lot on people so I asked and he says they've seen really good numbers on people using them, but they never share any numbers so might be marketing

Did some aero testing on the track (in late January) and on the road (in October) with this two configs :
- Garneau P09 open vent, Smith Attack glasses.
- HJC Adwatt with visor.

On the track HJC was ever so slightly faster (-0.001 so in the margin of error...). On the road HJC was slightly slower (+.004).
Even if it had been -0.001 faster on the road I would have sticked to the Garneau as the comfort level and ventilation is better for me on P09.

Just wished I had more time to test the way Campanaerts uses it with no visor. That's my mistake.

I would consider the HJC on a hilly course if it was fast without visor (the reason why I should have tested it... stupid me...) as it is a very light TT helmet without visor.

I've seen a couple of pictures of an Adwatt tri (with more vents) coming soon... something I may try for hilliers courses if weight is as low as the actual version.

Hope it helps.

I considered it before buying my Tempor. I was turned off by the high price from legit places versus the lower price from the Ebay seller. The ad description there didn't really match the item shown so didn't bite on the purchase.

I asked this question either here or on the UK TT forum before buying the Tempor and nothing but the sound of crickets.

I wish helmet makers for TT/Tri would get smart and do a ship/loan service with local certified fitters. Come in and toss the bike on their trainer and ride with the helmet for a quick video to at least see how it looks with your fit. Instead of buy/resell ad nauseum.