I don't think you would find them useful for kernel debugging. For debugging in general, they might help when debugging user mode crashes, that could related to these specific products (I don't think we do that too common, do we?).
Anyhow, I still have Chrome, Firefox and Citrix ones set in my _NT_SYMBOL_PATH, since they (especially the Chrome/Firefox ones) sometimes provide additional information when looking into stacktraces on XPERF logs.
It's too bad Nvidia and AMD (ATI) do not provide public symbols servers... I'm pretty sure these would come in handy.
