Stamina along with animation is a good way to solve the diving issue.
Getting down on the ground is one thing (unless you have nades in your pockets or you land on your keys.... that's always painful), getting up is the difficult part, epeically with equipement.
The prone is rather awkward in Heroes and Generals, but I use the Lgoitect G-13 so it doesn't bother me as much. Neither does crouching, but I know a lot of players dislike it.
In my opinion, the stand/crouch/prone needs to be easy and fluent controls. By using stamina and good animation, this can act realistic, look great and solve the dolphin-diving issue.
When it comes to bunny hopping, most games seriously over exaggerate a persons ability to jump. If you try running and firing while hopping, well there is a good chance you really aren't going to be successful any of them. You can't aim, you can't jump high when you are running or if you do you limit your running. So, if a game pays attention to how a person really jumps, bunny hopping will not become an issue.
Go ahead and put on 50+ LBs. of equipment, make sure you fill up your front pockets with some nades or extra clips. Then go sprint across a field, jump and dive into a prone position. Come back and let us know if you kept all the air in your lungs in the process.