"reliability is a very big reason why i decided to go with phases."
Are you assuming that the Phase has greater reliability or has this been documented somewhere?
hi eric, notice i prefaced my post by saying "i don't know how aptus backs respond in cold weather. . . ." my comment is not meant to be fact. it's only my humble opinion. the only back i can vouch for - the backs with which i am most familiar - phase backs. before i decided to go with phase i did a lot of "asking around". i asked a lot of questions of people who use leaf backs and phase backs. i tested leaf and phase backs. i personally like the heft and feel of the phase back. i like that the phase back is not plastic. i personally think that the fan design of the leaf back is a huge flaw, particularly if you shoot in dusty environments. i looked at the software associated with the back. the big deal maker for me is the software - the intelligence - of the back - c1 pro.
you say "that to have any meaningful answer we would need the total number of each brand in operation and the number of failures for each brand". even this would be incomplete information. in order to formulate something meaningful, you would have to know the circumstances under which each back was used. for example, some people are really rough on their equipment. you would have to know if the back was used for studio work or in the field. and if in the field, what kind of circumstances. . . .etc., etc., etc. so as you can see, it's not as easy as it might seem at first blush.
to a very large degree, a decision to buy one back over the other is a very personal "equation". some of the variables which are important to me i indicated above.