nothing wrong with the Jupiter lens, I use one on a Leica screw mount camera and love the results, and also the 2 lenses you name are both wide angle, indeed the 15mm is extreme wide angle,so for either you will need a seperate viewfinder, and the bessa is comes without viewfnder and rangefinder, so whatever lens you use you will need a viewfinder, which for the 15mm c, also can run into £200 GBP, would cost you more than the camera, also make sure that you have a 50mm viewfinder with the bessa for the Jupiter as without one it will be almost useless,Personally I would not get the Bessa L,
Richard