I will say it depends. Hose fittings are not held to any food standards. Brass pipe fittings can have surface lead in them and still be made safe(r) with a chemical treatment to remove the surface lead. Pot metal fittings can literally have any combination of brass, aluminum, copper, lead in them and do not lend them self to removal of any potential lead used to make them.
With that said many people use them and the potential harm is higher in the alcohol than the fittings made to use the product.
The gaskets or seals inside them may not hold up to high temps either, and the garden hose threads will require an adaptor to most valves etc. In my experience the garden QD's leak until there's significant pressure on them.
I think what you see in brass mostly come from mcmaster carr.
I used them for quite a while. I replaced the o-rings with silicone ones, but couldn't find one that was exactly right. They also have a tendancy to air bleed in the inlet side of a pump which is annoying as hell. Always connect them with the o-rings wet, that helps a lot with the bleed thing.
One last caveat, I've noticed that most home improvement centers have replaced the brass ones with gold colored aluminum. Feel the weight, the brass ones have some mass to them, the aluminum ones do not.
+1 on the the switch to aluminum in home centers. stopped into HD and Menards to pick up an couple sets at least for my chiller. They were not brass like they used to be--Guess the $5.99/set would have given that away.
Thanks for the heads up, I'll stay away from them for anything other than the older brass ones I have for my therminator.
I personally have not used them, but I know of quite a few from "The Green" board that have used the brass and rubber QD's from HD and Lowes. They seem to work pretty slick and I was close once to buying them myself before going to McMaster-Carr.
They do work, and work just fine overall. I bought my brass ones at B3, and was surprised to see 'Rain Bird' (the lawn watering equipment mfr) on the package. I later bought one of my sets at the local Ace to save a trip to Concord. And you do need the garden hose thread-to-1/2" NPT adapters, but the local Ace carries those as well here, so HD may.
As mentioned, the rubber gaskets don't hold up forever- I have to replace them every year or so, but the upside is that a 10 pack is less than 2 bucks at Ace.