I logged around 20 dives at Dutch this year, June and August. I wore a 7mm one piece, 5mm hood and booties. A pair of reef gloves, and I was comfortable at depth, far too warm on surface swims. Hands were a bit chilly at depth, come to think of it.
I did see one guy dive a shorty, in August. He went to the platforms and thumbed his dive. I ran into him later, he said it was far too cold, lol.
Next year, I'll be diving dry there.