generally I've found that I get a hit rate of about 65%, with my average win over the last few years being nearly 3 times my average loss.I should also point out now that I'm in australia trading the asx, which has been in the middle of a rampant bull market, so my figures are probably going to be a bit more impressive than if I was trading in the U.S
prior to the recent commodities boom over here, it was more like 55%, with my average win being twice my average loss.
If you end up going with the adx(and hopefully the dm+/dm- to go with it!), look up some info on wilders extreme point rule, as it helps to weed out some of the whipsaws that you'll get in a non trending market.
Another thing I've found that really helps the adx system is to overlay a group of moving averages on the chart. using a 10/30 ema crossover, or 5/15/30 ema(looking for averages to be stacked in the right order), will greatly help with the success rate of the system.
For me, the macd is just another guide that I use to help the adx system by looking for divergence before I enter a trade, but how you use it will be ultimately up to you.