I'm much less likely to screw up using a diaphragm than a wing bone.  I've gone through years where I dedicated all my calling in that season to using a single type of call, just to improve my calling skill set and versatility.  One never knows when you're going to lose or damage a call and it seems stupid to limit yourself to a single type of call.  Thirty some years ago I slipped on a rock when crossing a creek in a hurry and fell on my old Lynch, which broke it.  I wasn't a good enough caller on my diaphragm to convince the gobbler to investigate the noises I was making & he left, so from then on I started working on learning one type of a call at a time until I was proficient on multiple kinds. 
To be fair, I have spent the least amount of time practicing on a trumpet or wing bone. They definitely take the longest time to get the hang of.  I've probably killed the most birds with a slate, then a diaphragm, finally a box.  These days I use all three almost every time I hunt.  I have heard some great trumpet and wing bone callers, but I'm not one of them.  Count me in the diaphragm group.
Jim