why pretend to justify? the backs are cheaper then a 1dsmkII and give you better files! i don't hink you need high iso for macro or landscape, and at 100....no comparison.....i used to have the P20.....great back...the cable is fine, you won't even notice....the problem i had was that the camera all of a sudden shows it age.....high end digital and 40 year old technology on the other.....it will work fine, but.....just my personal opinion.....