--- best alternative to sugarsync --- I've been a long time user of sugarsync "free" version, one of it's top feature was custom file / directory mirroring + collaborative folders sharing & edition, on multiple devices..
This far I haven't managed to map a shared folder with skydrive on another person computer ..
bitcasa doesn't update files within those ..
Google drive does ..
& you can create "LS" directories ( symbolic links ) to real directories to do as sugarsync used to do !=)