It's been a week now since SSF started trading. OneChicago didn't get SEC approval until the day before SSF started trading, and their system has been briefly down a couple times. NQLX doesn't seem to have had any problems. Have you traded SSFs? Have you used both exchanges? How did they compare.
1CHICAGO was down quite often for short periods of time. NQLX I have seen down only once (30 minutes, yesterday).
SSF is too risky for small traders and investors. The biggest problem is liquidity. The risks of low volume (current state), potential zero liquidity (halt on individual issues) and potential abrupt leverage (large gap in stock prices) are so high that small investors cannot afford. IMO, SSF has to be just a component of a complex strategy involving cash/options markets. I trade no SSF and need at least a $50K trading capital before considering it.