ATM Spider vane thickness vs. performance

[BodyByJay@aol.com]

In evaluating various secondary mirror assemblies I find that there is a
fairly wide variance in vane thickness between different models (some are
twice as thick as others).  I am not talking about the vane height (edge to
edge) but rather the thickness (surface to surface).  ProtoStar's vane
thickness is 0.018" and other models I have seen range from 0.026 to 0.030" or
more (coating it with Krylon UFB could add another 0.003".)  Now tell me... 

1) Isn't it best to use vanes that are as thin as possible?  

2) Don't thinner vanes mean less diffraction?  

3) Doesn't the area obstructed by the vanes themselves (lenght of vane within
light path x vane thickness) also contribute to obstruction of the primary?  

4) I know this may be extreme but if you want to squeeze every bit of possible
performance out of your scope maybe this is important?

What do you think?

Jay D. Anderson