Anebel - You have missed the point on both the threads - as you aren't prepared to look outside the square.
Quote Bobthebuilder - "So my question is- is it possible to do dressage properly in a bitless bridle?"
Answer - Yes it is possible - its as possible to do as it is in a bitted bridle - if you are the right rider.
Quote Ceasar (can drafts tdo good dressage thread) - i am a taller rider at 6'5 but im not really heavy for my height (185)... I was wondering if drafts often make talented dressage horses and if so which types in particular?
Answer - They can but it is rare - they are very active horses with strong quarters but often lack the ability to lengthen. They are easy to train and are less likely to stress.
In an ideal world if you are a dedicated dressage rider with high ambitions you obviously won't look first at a draft or one that is ridden bitless. Bowie the Clydesdale was in fact a top level showjumper until an injury stopped him jumping - so drafts can be awesome competition horses. Warmbloods may be bred to do dressage but there are many around who are not able to do dressage beyond 3rd level.
For the majority of riders - going to the top is not on their wish list they want to enjoy their horse. I bought myself a warmblood when they first becme fashionable but sold it on as it was boring to ride - I loved my TB and took him up to Open Medium before Navicular forced him into retirement.