If I may add my experience with Origin8. I have had alot of bikes and I like the Origin8 'stuff' - they produce a great deal of things (made in the same factory as everything else) and provide a great value at sometimes 1/2 the cost of name brands -and frankly, alot of their stuff looks better and works the same - than name brands. And, no doubt, some of their product is totally cheesy and meant for the Huffy's of the world.
That said, their headsets, I'm not quite sure of....I'm a King guy. The expander plug, though, I had, tried....and didn't like. I tried, and tried, and tried to get it adjusted to no avail. I mean, a quality headset's adjustment is literally a 20 second job, if you're on your 4th, 5th, 6th try - I bet you are having the same issue as me. Decent headset - lousy expander. I didn't really investigate much - I got a new one and haven't looked at it since - I mean they are $20 at any decent shop.
Are the knurls not knurled enough?, the spacing betweem the top of the steerer tube and the top cap not correct? (Moots plugs at 5mm, Kings are more like 2mm, Origin 8????). I don't know and for $20, I didn't care.
Note, though - take your fork to the shop as (like anything in the bike world), some expanders fit and work better than others. Some with the rubber expander - good idea, but the rubber can dry out over time - making them 'smaller' in diameter.
This is an interesting issue though.....let us know.