I am 100% sure anyone who has played through parts of the FS2 campaign know what I will be talking about...
What happens when a wing of eight SF Maras jump in 300m away from you? Quite simply, you will most likely lose that fight.
I was playing a Terran Gauntlet with 2 respawns. The first three wings of fighters were easy, though my wingmen kept on dying. By the fourth or fifth wing, I was alone with 2 spawns. All of you know what happens when a wing of Myrmidon jump in halfway through the destruction of another wing. You are swamped... quickly. A loadout of 3 Stiletto II's, 2 Infernos (I think), and 24 (i think) Hornets on a Myrmidon using a Subach HL-7 and a quad-firing Prometheus S. You easily survive because of maneuverability and speed, against the Herc Mk.II's in the gauntlet. However, what happens when you are swamped with 4+ equals? Most of us can take 4 myrmidons in a 4-on-1 dogfight without losing. Sometimes you get lucky and make it out with no damage, sometimes you are dead with a hundred missiles locked on you. It's all about timing.
So, what does that have to do with a Sathanas v. Orion? It should show that, in a fair fight, either could win.
I actually recommend someone FREDs a mission for Karajorma and TrashMan. Put in that mission, built for a clean build of FS2 retail. Karajorma, take control of the Sathanas. TrashMan, take control of the Orion. Duke it out, starting the mission in a broadside (both jumped in next to each other). Beam-free-all for both, and take control. I recommend both of you try to outmaneuver eachother.
In that mission, If I was the orion, I'd try to take out the Sathanas's engines, and blow it up in a blind spot. If I was the Sathanas, I'd try to use my HP and ram into the Orion, until that ship blows up (fairly quickly, mind you). Remember that the Sathanas has both speed and up-front power. The orion has maneuverabilty and spread weaponry.
If the FS universe was the same as our own, I'd put money on human determination, and say the orion will win. A good captain would disable every beam possible before the second salvo. The terran captain would have to be desperate to take on the Sathanas 1v1. Sufficent maneuvering and disarming the SJ should be sufficent. Remember that the Shivans are colony-minded. Do what is best for everyone, even at the cost of yourself. They would probably do anything to win, if it was for a goal.