damion said:
You still need to use an 8 speed chain with a 8 speed casette, a 9 speed chain with a 9 speed cassette, and so on.
I first began using SRAM PC59 9 speed chains on Shimano 8 speed XT cassettes in combination with a 9 speed crankset. SRAM 9 speed chain shifting on 8 speed cassettes was flawless, and I eventually used on one a 7 speed cassette with a similar hybrid drivetrain. Fact is, I've been so pleased with their PC59 chains I still use them today on my singlespeed-esq Speedhub, Nexus and Spectro drivetrains.
The theory at the time was that SRAM 9 speed chains were a fraction of a gnat's eyelash wider than a Shimano 9 speed chain, based on manufacturer data. That may or may not have been debunked by some careful measuring by others on the board, the whatever the width, I've been pleased with their shifting performance on 8 speed cogs.