One little tidbit to think of when comparing a aircraft that was designed as a transport and being used for the paratrooper role, and a bomber being used for dropping paratroopers is the airspeed at which you jump out and "hit the silk".
The C47, C46 and Ju both could slow down to a reasonable speed and have the troops jump out with a reasonably spaced stick, with the aircraft still at a safe speed above stalling.
The bombers on the other hand would need a higher airspeed with the attendent problems of troop dispersal and/or eqmt being ripped off the bodies.
In my skydiving days, on exit, I noticed you can definatly tell the difference between an airplane going slow and and airplane going fast. And slower is safer (for the skydiver)