I suspect that those who have been immersed in cold water would put the dry suit first.
Spot on
Well with the benefit of (military) experience.....You can guarantee getting into the dry suit,..assuming you put it on before you go flying.... but despite all your preparations and training you can never ever guarantee getting into the dinghy... it may not inflate, and even if it does you might not have enough strength / feeling in the hands left to climb into the thing.
If you have a working PLB/ELT the SAR guys will get very close to you, even at night, but don't underestimate the simple stuff such as reflective strips and salt water powered lights
And as Syllo.....
said
Unless you've had first hand experience of sudden exposure to cold water, you are extremely likely to greatly underestimate its effects
Oh yes, it's really impossible to underestimate just how hostile the Sea can be.....