Quote - Even using the right tools, SSS is not an easy thing to control, much less master - speaking as a hobbiest myself. Almost every setup is different, requiring endless extended test renders, tweaking, renders, tweaking, etc.

Not entirely true. You just have to understand how it works and what it's supposed to be doing. If you go for a pre-conceived "look" about an object with a render engine such as Mental Ray (I'm not going to say the L word, since it seems to upset people), you are likely to have problems.

But SSS is at it's most "real" when you have a competent render engine that is capable of a good degree of physical accuracy. At that point you decide what your object is made out of and adjust settings accordingly. Meaning,  for example, SSS settings for skin won't likely make a convincing candle.
Really, it's a matter of knowing your surface properties, e.g., refraction, diffuse, spec and so on, but also being able to set up your lights to show off the SSS effect. And of course you also need to know your scene parameters and particularly your object's size and thickness and how it relates to your scene size and lights.

In the end, it's not that much guesswork, but good setup and taking the time to consider all the scene variables and plan accordingly.

Poser, on the other hand, has no "real" SSS, and its lights are problematic and terribly unrealistic at best. People like bagginsbill can beat it into submission with pure mathematical knowledge of what Poser is up to under the hood, but that's Poser's trip and very little you learn in Poser is going to help in Maya, for example (Not gonna say the L word....), because Poser is... Poser, and while there's a certain degree of unity among most 3D apps regarding basic principles, Poser just does things.... its own way. Even something simple like a directional light - you can learn to master how Poser does it, but then give it a shot in Maya and at first you'll be lost with all the settings that Poser never taught you. Learn how to render with Mental Ray lights and shaders, and you'll be blown away at how much Poser lacks.

I'd love to see bagginsbill dig into mental Ray nodes. I can't imagine what he'd be able to do with them, considering his penchant for mathematical thinking.