I've got an iMac G5 which has experienced period kernel panics taking down the whole system since I started running SL 1.9.
So, 1.10.0 (32) ran here for a couple days. During the time, the client quit or hung on me four of five times. But it was only the SL client program that crashed. The rest of the system was unaffected, as is the case with every other piece of software that runs on this machine.
I've now switched to 1.10.0 (34), primarily to get rid of the 'stutter' when crossing boundaries or otherwise being exposed to many new textures at once. I've had one crash with this version, but it took down the whole system with a kernel panic, with the same basic footprint that 1.9 had.
In an ideal world, there wouldn't be client crashes, but if there are, I'd much rather they not take the whole system with them.