very high [smooth] still appears jerky
That's very subjective. If I do:
Random(1.0)
Hold(0.5)
Smooth(0.1)
It looks perfectly non-jerky to me.
Even if I do Hold(.1) it still looks non-jerky.
And there's still a lot of room for more smoothing. And of course you can just use multiple smooths if you need to (although I can't imagine you would!)
I really don't know what visual effect you're after so that's why I asked for images or video. But other than that, I have to say that smoothing random values isn't really a worthwhile exercise -- it means you don't actually want truly random values after all.