I had no idea the $2 Dow e-mini even existed until August. But since then, I've used it a number of times profitably. I'll switch to them whenever the craziness level gets a little too extreme on the SP-eminis for my account size. Granted though, you can't trade them for 2-3 points, like you can the S&Ps. But they ARE good for the broader multi-day trend-trades, or, in my opinion, for higher-risk/high reward trades that you might not want to attempt with the SP-eminis, but have a strong feeling about (like those "sloppy" days when the SPs keep trying to punch through a strong resistance or support level for most of the session, and you sense an end-of-day reversal coming - but you can't always find a high-probability entry point for the SP-eminis. Or event-driven bets on big earnings news, fed meetings, economic data, etc).
Granted, a trade with the $2s is a lower-profit trade range-for-range with the SP-eminis. But I'll hold a $2 overnight or for a number of days (if I think the odds are in my favor). Its rare that I'll do that with the SP-eminis.