if yo go for a butter, often refered to as muskateer coin, then get the 50p version, bigger more visual better for stacking, my 10p version came with an american version vid so was basicly useless for setting and stacking.
regards the hopping and butter examinability you would not give out your coin unique for examination before the trick is done.
if memory serves chinese bit is closer to hopping halfs than coin unique.
also if you go for the sun and moon set it comes with all coins needed, i use this set because one its cheaper and two the coins are gold and silver colour like the sun and moon and are unlike regular coins that they have special properties.

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on a sub note hopping halfs comes in two varieties when considering an american set which alows you to do some extra coin effects due to the nature of one of the coins, that combined with the other special coin in the set will give you two of the best gimmicks in coin magic.