If you can't express this problem in numbers then you really dont undersatand it. There is a very simple formula which goes like this:

Ns = PI^2 EI / L^2

Where:
Ns = The theoretical compressive capacity at the servicability limit state
PI = The constant 3.14159
E = Modulus of the material
I = Second moment of area about the neutral axis of the cross section
L = The effective length of the member which is a function of the actual length and the end restraint conditions

If you understand that then you will know that no bike wheel built to the proportions of standard bike wheels will ever be able to gain any significant strength through using the spokes in compression. That includes R Sys and any other wheel. Unless you significantly change the spoke dimensions (this is a geometrical problem) then a spoke simply cannot be of any real use in compression. I suspect the Rsys spokes are at best able to remain stable when the tension is released at the bottom of the wheel and dont actually really go into any significant compression during normal use.

As you can see from the formula, you can increase EI as much as you like (hence Rsys large diameter spokes) but the length is what really matters (hence Rsys restrained end conditions, at least i think they are, maybe), but if you want spokes acting in significant compression, you need them to be VERY short.

Just the 2 cents worth of a structural engineer....

Edit, Having said that I have never actually analysed an Rsys wheel so it is possible they have squeezed some comressive capacity out of them. It wont be much compared with the tensile capacity though.