I am anxious to see if John agrees but it has been my experience that Azalea do not care about substrate BUT they do like to be damp NOT moist. So the answer would rely heavily on how often you can water to maintain damp soil conditions(at least here in the NE). They do throw a LOT of fine root so for me a 50/50 mix of Dry Stall and topsoil works out great but only because they get water 2 times a day as needed to maintain moisture in Spring and then 15 minutes 2 times a day with auto watering throughout growing season. I only Fertilize one time in Spring and only a 2 maybe 3 times during grow season as they are a shrub and therefore get treated as one. Just my 2 pennies
It is very hard for me to say what will work best for you...I do agree with everything Grimmy said and would add that azaleas hate to be dry as much as wet...moist is the goal.
For me soil is part of a bigger equation. Your environment and your dedication to the care of your trees are the other variables. Your trees will tell you with their vigor and health when you have it all balanced. For me watering is the variable that can be used to compensate until the right formula is achieved. Material with a large foliage mass tend to get dry faster...less foliage stay wet longer..
I am sure people will say I am nuts, what's new, but I wasn't successful with azaleas until I stopped using bonsai soil with them... I use a peat based potting mix with bark and perlite...whether the tree is in a nursery or bonsai container. I repot after 2-3 growing seasons and seek a container volume that will nearly dry out daily given my watering habits and the foliage mass of the tree.
Its never perfect...at least not in my garden...its ongoing challenge to provide optimal care given changing conditions...you have to pay attention and make changes based on the health of your trees.
I am not saying this will work for you...let your plants tell you what works best!!