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Given these facts, there is absolutely no reason to level professions with your character unless you want to "experience" leveling them up. That's up to you. Increased mount speed and flight @ level cap will make the process much faster. The gold you gain from leveling is more than enough to purchase flight training. Be sure to gain rep with your appropriate capital (Stormwind or Orgrimmar) to get a significant discount on flight training.
Before I go ahead and settled this debate for good; I spent most hours surfing the .net to get an idea of what others were saying; if you have done the same you will probably find similar results ~ that in the general publics eyes, WoW Dugi Guide vs  WoW Zygor Guides is pretty much even.  U also probably found that a few opinions were biased towards the guide they owned.  These findings aren’t very helpful in finding an outright winner however; they help show the fact that with what ever guide you end up choosing zygor and dugi guides, you will should be very satisfied!