Hmm. I am not sure such a technology exists. We are using a standard “cloud-based Sync model” where EndNote Web is our cloud. I am not familiar with any other software tools that work across Windows Macintosh and iOS that use a different approach but am happy to look at examples if you send some along. If you want to plug your iPad physically into a Macintosh and move files using iTunes, that could potentially be an option but I very highly doubt that would be more efficinet.
Jason Rollins, the EndNote team