DWC.. with NO Hydroton

Do you have to use a growing medium,
ie: hydroton

Has anyone tried it without?

Kinda like a DWC meets Aeroponics?

I was thinking 2-3" netpot, with a neoprene collar holding the stem in place, roots growing through the netpot, directly into the nutrient formula bypassing the hydroton.

I'm not sure why you would bother with that. A little hydroton is cheap and easy. Plus it blocks light from the res.

do some reading here, lots of people do that same thing with good results.

I use just collars blocks light fine

You dont have to use hydroton but something that blocks the light from the reservoir is highly recommended
I have used coco blocks in 5" net pots with good results like these ones here & put a layer of pebbles on top
http://cgi.ebay.co.uk/4-Jiffy-Coco-Coir-Block-x-6_W0QQitemZ280387536879QQcmdZViewItemQQptZUK_HomeGarden_Garden_PlantsSeedsBulbs_JN?hash=item41486647ef

Yeah, using neoprene sleeves will work, just make sure you dont pinch the stem to tight. I'd even suggest cutting the bottom out of your net pot for easier access maintanence wise. You will have to dial in water level and amount of air being pumped (bubbles) but that comes naturaly with DWC.