The Audiomods is a modified Rega RB250, albeit with new bearings etc. The arms are quite different structurally.
I have actually heard both arms on a Rega P9, the RB1000 was more precise sounding, and to my golden ears cleaner and more articulate, provided the VTA was dialed in on both arms.
Agree with the Helius Omega, an interesting arm, and SME IV, they are both good options and to my ears superior to the Rega/Audiomods.