I have three Macs (identical OSs) on which I use Endnote (identical versions). I sync a single reference library that I use on all three Macs through Endnote’s own online feature. Although the number of references is synced correctly (I e.g. currently have 1909 references in the libraries on all three Macs), each time I update the citations of a given Word document on a new Mac, I have to search and verify the references one by one. In other words, Endnote on Mac 2 doesn’t recognize the identification numbers of the references that I’ve inserted into my document on Mac 1. This is very inconvenient and annoying if one has, like I do, large monograph size documents and multiple references from the same author and year. Support forwarded me to a workaround, but it is not adequate. I used to sync with the free version of SugarSync which worked fine, but other cloud solutions seem to clog the Endnote library with clutter until it crashes. This is a major disadvantage. Endnote needs to find a solution quickly or else professional users like myself will start migrating to other bibliographic software (and recommending migration to our students, as well).
I agree, Endnote’s use of record numbers leads to these kind of problems. No easy fix other than completely reingineering Endnote’s database structure.
I use an odd method, not sure if I would recommend it but here it is. From one computer I store my library in a synced folder (a Syncplicity Share). But I also connect this library to Endnote Sync. Then on the next computer, instead of starting a new library and syncing down all the records, I copy over the entire library and data folder from my Synplicity folder to a local folder on that computer. Then I open this copied library and connect it to Endnote Sync.
This way the record number for all existing references will be identical on both computers. Then going forward I just add references to either computer and let it sync via Endnote sync. I haven’t had any problems this way. Technically it would be possible for both libraries to assign different record numbers for new references but I haven’t had this problem yet. If I do I think I will just copy over the whole library from one computer to the other again.