Interchangability between drum programs?

 
  Can the files from one drum software manufacturer be interchanged? I seem to remember this was the case from some other posts I have read here. I know you can use any midi loop with BFD eco because I have already done that. BFD,EZD seem to easily import any midi drum loop. Is this where the interchagability between manufacturers ends? or can I actually use a file from one in the other?
 
 If all I need are drum loops I can buy midi loops without purchasing another program. I guess I'm a little confused. It seems like there is interchangability but I'm not sure in what way or how far that can go.

In most cases you won't be able to combine drums from different manufacturesas they use propriatory formats (an exception would be kits for Kontakt. I could for example create a new multi with a combination of Steven Slate EX and Neil Peart Drums).

You could however run an istance of each. There was a post here a couple of days ago explaining how to use a drum map to send a MIDI track to two instances of EZ drummer, you could apply those principas to, say, an instance of EZ Drummer and an Instance of Eco

Kits can have many non standard key allocations to allow for different articulations. This can mean midi loops may play differently on different VSTis. Drum Maps can help here too.
 
Edit - and Striky is right - EZ player pro makes it easier.