I built the Dynacraft DI 21* and took it out a couple days ago. Not much luck on a day with all bad swings. The head is much too light in weight though, even after adding weight when building(graphite shaft); lighter than a 'standard' 4i head.
I also have those Bombtech driving irons, but think I'm going to return them, unused/unwrapped. Just doesn't have the 'look' of something I'm going to be able to hit properly.
Also have the Bombtech hybrid set, which I used only a couple times last season. Steel shafts, that need to be switched out to graphite, which may make them usable.