Would like to know if each & every outlet stone from Kurokigoishiten is imperfect in some way or are there only a few mixed in with perfect stones? I am interested in the "Clamshell Go Stones Size 37, Snow Grade (outlet) 10.4mm.

I have two sets of his "outlet" stones, and I honestly can't tell you for sure. The flaws are all very minor (at least in my opinion)--none have chips or major cuts/scrapes, and all of mine sit well on the board. Often, they are slightly misshaped, have a tiny discolored part or black speck, or the stripes aren't very visible. But unless I was looking at them very closely, I wouldn't be able to tell.

I think, in theory, they all have minor flaws, but I can't always find them.

The black stones are normal, by the way.

Thanks for letting me know about your "outlet" stones. I'm willing to put out the bucks, but don't want to be surprised or disappointed. Still a little leary of the 10.4mm thickness as far as actual play. Considering a new set of 8.4mm stones.

Do you prefer thinner stones to thicker ones ?
What's your experience with various sizes, with both thinner and thicker stones ?

Only have 1 set of used flat stones, so only know what I've read.

There's a learning curve to Go equipment, just like to Go itself.
If we have the chance to use different boards and stones and bowls, then over time,
we can find out our preferences. A few years ago I asked Mr. Kuroki what was their
best selling size stones, I think he replied size 35 (or 36 ? I don't remember now.)
I heard Cho Chikun's favorite size was 38 (10.7 mm).
That's also my favorite slate & shell stones size (for home use).

For coffee shop, regular Go club use, I like the 10+mm ING weighted plastic stones.

Mr. Kuroki sells sample packets of 10 stones each --
if you like, you can order different size samples.
But it's only an approximation. To find out how it really feels
with a particular size, it'd be nice to use a complete set over
some period of time (say, a few months to a year, or more).

Of course, time and budget are usually also factors as well.

What we read, hear, and see are not always the same as direct personal experience.

So it also depends on how picky we are about these things.

Thanks for the info. Will take it into consideration when I decide to get a different set of stones.