So its my understanding that a twin tube or hydro shock will foam on rough roads and hence fade.

Nitros or monotubes do not do this.

However, what about a shock like Old Man Emu that is nitro AND twin tube?

 

Nitro = gas filled = no oil to foam up.

 

What kind of shocks are the stock Rubi shocks?

Flash

 

Even if they are twin tube?

Also the rubi shocks are nitro, I believe all Jeeps shocks are. The X and Sahara models are low pressure nitro.

 

Many Nitrogen charged shocks still use oil for damping.

Valving is much simpler for a practically uncompressible fluid like oil than for a gas like Nitrogen.

The pressurized Nitrogen is there to avoid the formation of bubbles in the oil which do compress and lead to fading.