I've tried using all of the medic weapons to get a feel for all of them, and I came to the conclusion that MP28 is an obsolete gun. M1928A2 is my 2nd most used gun in BF5 and it's simply better than MP28 in every aspect. They both have 50 round mag, MP28 shoots slower and got much higher recoil.
I can easily control M1928 when ADS, not the case with MP28. You'd think that it should be a very easy to control gun since it fires smaller round at a slower rate than M1928, but no. It kicks all over the place giving you no chance at medium range.
One could argue that MP28 got a better hipfire, but from expierence I can safely say that the difference is so small that it doesn't matter one bit because M1928A2 got higher ROF to compensate for that.
There are a few more examples of one gun being better in every aspect compared to other guns, but this one stands out the most. I think devs must do something about it. Maybe reduce recoil significantly and nerf hipfire to make it better at medium range than M1928 but worse at close range.