Poker - Since the system is based on the NDX (plus some help from the broader Naz breadth data and various P/C ratios), the Qs and related derivatives (QLD, QID, and the E-mini NQs) are all directly applicable, so the choice of trading instrument is a personal one based on how much heat one can stand when the market moves against the signal. Personally, I like the NQ futures (~24/6 tradability and Stop protection), plus the advantages that accrue at tax time, i.e. just the bottom line, no wash sale crap to deal with.