Yeah, I think a tube made from natural material has a sound with so much more personality.

Making one from plastic, tends to have a very uniform sound to it, the resonation is always exactly the same.  To me, they sound....well...like plastic.

When it is made from a natural wood, there are little pockets of air in places inside the cellular makeup of the plant & build ups of more solid/harder areas too, which create different resonances & overtones when held or played differently.

I guess this might also be a reason for a beginner to start with a PVC/etc... one too.  Might be easier to learn how to play without all the variations in overtones.

Since a Didgeridoo is a resonator type of instrument & basically makes just one note, all the variation in sounds

that it may have, comes from the harmonics & overtones created from the tube resonating & from sounds made in the body & mouth of the person playing it. 

So for the richest overtones & harmonics, you'd want to use a natural source with more of a non-uniform makeup, that is not too dense & not too light.

2-cents...

WS