Well in my experience peoples responsibility tends to end just before the point of having to pay to replace or repair something they screwed up. (It isn't a by mistake you found Dwayne... he doesn't have a reputation for making excuses for anything he fell short of doing. AND FWIW as pointed out here it's a 'cheap/undercutting' copycat of another head already manufactured. )
Don't take this the wrong way but there are people out in the world who echo what you have just said but it's a different story when their own stuff is involved. (Thank you ...I don't fall into that category)
The problem with what you said about responsibility is that it gives people the green light to put the absolute minimum effort into something and then use that excuse as a get out of jail free card when there is a problem.(I understand your point and it is AS BROAD as saying "fix anything that is wrong" especially when you didn't give him the indented rocker gear which AS THE BUILDER you'd catch this when you check geometry and fastener engagement and etc...AGAIN where does it end 'fix anything' seats LOOK to not have enough press and with that roller cam your running I took it upon myself to put copper seats in properly because I also think you'll need Ti valves. "So I fixed 2 issues at the same time" In one of your replies you even said " I AM THE RESPONSIBLE PARTY AS THE END BUILDER" how would you even charge for 'fix anything' NOONE would even want to pay for that especially on a unknown, AGAIN cheap copycat, head. That is really especially specific and has direct reasoning as to why fundamentally if you WERE disappointed, you'd been wrong IMO. )
Example:
Imaging you brought me a carb you had just purchased. You tell me to go through it and fix anything it needs. I give it a wash, check the jets , replace the power valve and gaskets. You stick it on your engine but it runs a little rough but not too bad. (OK so I got a carb from you put it on and it runs bad but I use it anyway?) You take it for a drive anyway but it starts to backfire up through the carb, as you try to get home it backfires so bad that the air filter catches fire and you get some heat blisters in the paint on your bonnet. After another inspection of the carb it's found that the emulsion tubes weren't machined correctly and that was the cause of the backfire and damage. So you come back to me as your bonnet sits there still smoking and ask me why I didn't see it or fix it especially when you told me to "fix anything".( well now Thumper and a lot of carb builders actually TEST the carb they go-thru or build)
I say to you that it's a major operation to get to those sealed in emulsion tubes, also I've never seen that problem before. I then shrug my shoulders and say "hey man... where dose my responsibility end?" and promptly show you the door.
I'm sure you'd be a very happy camper after that...
(I don't feel this is a representative comparison of the current situation. )