Interesting question. I have seen more successful in hospital intubations done with bougies than inter/pre-hospital ones. I wonder tho if most of it is what you get used to. Learn to rely on it to much when you have a kit that does not give you accessibility to one. I've only seen 1 tube successfully placed with the use of a boogie.
I don't know that really make a big difference in success rate. If you're used to using one, chances are you will make it easier on yourself if you continue to use it just be careful the day you end up in someone else's truck and there isn't one available. On the flip side, as I posted above most paramedics I know never use one during their intubations and tho the complicated airway shows up from time to time, they never use one.