this may be a stupid question, but can i use those big net pot/lids, (the ones that fill up almost half the bucket with rocks, normally used with drip systems), but for dwc, rather than the standard lid with a hole cut out and a small net pot? would there be a difference,other than price of rocks, between the two?

Yes, you can use whatever you want to hold your plant in a dwc. Just make sure your roots stay wet and oxygenated.

the more room the merrier man ,
the 10in. lids hold lotsa hydroton n give you lotsa ballast when growin trees or large shrubs . less apt to wanna tip on ya .
peace
crispi