I use three Spyders with Obyron all the time, sometime with an additional Overlord/D-Lord, as a threat they are great, either taking an entire turn shooting or assaulting the turn after. I often split Obyron/other characters off at this point to threaten more backfield units. All things considered Obyron is not that expensive compared to a basic Veilteck.
I have tried Particle beamers and found them wanting, due to cost and how often the spyders die to save the rest of the army.
I wish I could field an army of only spyders, scarabs, wraiths, and the forgeworld necron bugs. But that is not relevant here.