it comes both with pros and cons.
if you're a newbie - you shouldn't go for them because you get multiple steroids from the same shot, so if you get side effects, you wouldn't know which of those steroids caused them.
if you're already experienced with all those steroids (separately) then the stack is great because you get all the steroids you need from a single shot (so you need fewer injections).
another problem COULD be that it a stack may cause more PIP, but it is still worth giving a try and check if you would experience it or not.