I have stopped using Shimano chains myself. I find the whole different
colored pins for single use in the 8/9/and 10's to be another source of
confusion in my life, and teh whole business about only breaking the chain
once at a particular location and the directional orientation of placement
of the pin in the link simply adds to that.

I don't run anything with more cogs than an 8, and both sram and the KMC
chains up to that work fine on the Shimano equipment I own...maybe a dozen
or so bicycles.

Having said that, I think the advice about don't use a 6 speed chain on 7 cog
rears is probably good advice.