Hello I am looking into the ALPA reflex cameras. I have found several references stating that the "ALPA 11si" had improved "mirror" and "shutter" compared to the "ALPA 10d". Can anyone tell me what these "mirror" and "shutter' improvements were, and are they really noticeable? I am finding very good copies of the "ALPA 10d" at much lower prices than the "ALPA 11Si", and I really want to know if these "mirror" and "shutter" improvements are worth the extra premium. (by the way, I am very aware of the differences in meter functions between the two cameras. However, this is not a deciding factor for me.) Thank you all in advance for your help.