After briefly skimming this thread, the problem with subliminal messaging is that very little accurate research has actualy been done into it. According to what I’ve read subliminal messaging may be no more influential than normal overt messaging.
Also Derren Brown is thought to sometimes use mathematical and standard magic tricks rather than psychological tricks. The author Simon Singh has tried to prove, on a few occasions, that Derren Brown uses no more psychology than most magicians. Brown’s television program isn’t conclusive proof for subliminal messagings effectiveness.
In conclusion subliminal messaging might be useful or might be just a placebo, if it works stick with it. If it doesn’t there are other, more well founded techniques out there.