I made a milk stout once which called for 8oz of lactose. I found it too sweet, also had SWMBO try it without telling her about the lactose and she also picked up on the sweetness. I ended up tossing it but that's very subjective. The beer technically was good I just found it too sweet. I was for a 5 gallon batch.
Jebus, I didn't plan on actually trying it to get my level of sweetness down. When I bottle I just want to get it over with as quickly as possible. I was thinking about boiling a pound in a couple cups of water and then adding 1/3 to the whole thing and for the last 12 bottles or so i'll add some more.