Delta, to me, is something that always looks better in retrospect - there's no doubt in my mind that the pattern is almost blindingly obvious in many charts after the event. The pattern is also very much out of whack in some as well - but that's okay, commonsense dictates you'd ignore charts that fit badly.
Delta, sadly (personal opinion) always looks better in retrospect because a turn will be obvious after the event, but on/around the predicted day the turns often just aren't that obvious. It's not uncommon to see a small feature that confirms it all, but you don't recognise it at the time. There is no guide to move distance, a swing might play out in a couple of days - you can be out of pocket despite getting it spot on, as the swing you traded was quite small and the reversal was big and fast.
Inversion - call me cynical, but Delta theory says either side of point one and nowehere else.... I'm darn sure that's incorrect, and extra swings that are in addition to the solution are quite common - it's okay to suggest they don't count, but they often move as far as, or further than the official move - in reality you can't happily trade a 2% move and ignore a 4% one that isn't officially there.
Finally, the newsletter itself shows that the guys with the inside track don't get it right, and indecision is rife... I'm a Delta fan, oddly enough, as it shows me that there is order in the markets - it just doesn't show me it in time to make a profit from it. I'd not want to put anyone off trying Delta, I think it's something most people would benefit from seeing in action as part of the learning process, I don't think it's a trading system for the majority of people trying to use it. I imagine there are some people with a bit of a knack for using it who do very well. Anybody selling it as a cure all, the secrets of the market etc etc is being a bit economical with the truth in my view.
Dave