For those of us with Interactive Brokers, a search for "ER2" contract shows listing only on GLOBEX. Is the russell contract traded on ICE accessible for IB customers?
The real issue here is volume. For myself, the transition point is when regular session trade volume on the ICE contract exceeds that of the contract on GLOBEX. Until then, I'd rather continue trading on GLOBEX. In any case, continued observation of BOTH contracts is pretty important.
The ideal situation would be one where the majority of volume swiftly transfers from GLOBEX to ICE. If the volume trickles out, it could get messy for ER2 players.