Thanks for sharing your experiences with this, Daniel. I'm in a similar situation as you are, in that I actively collaborate with at least one other person on our family tree (my grandmother, mother, and myself; others tend to provide us information to integrate into the tree, rather than actively collaborating).
The difficulty I am facing is that it is technically extremely difficult to work on the same tree across 3 different states, for precisely the reasons you mention.
Now, Ancestry.com has a great feature for building my tree online and inviting other to contribute. This is great, and answers the collaborative issues, however, it lacks the detail and sophistication of the desktop application (which is why I bought FTM).
Because of the technical issues of Ancestry.com only allowing me to import or export GEDCOM files (and not the data as well) this puts me in an awkward position of having to keep two sets of "books", which is very undesirable, because so many things can go wrong (missed data, media, errors, etc).
In my ideal scenario I would like to build my family tree with all the media and attachments using FTM, then upload everything to Ancestry.com and share it with everyone else in that manner. They in turn can make updates, additions, contributions there, which I would then be able to synchronize with my local tree in FTM. This way my local copy would act as a baseline, and I could use it to create books, burn CDs, make backups, etc.
To be honest, I'm a bit surprised that this isn't more of an issue with other genealogists as well, or is it that there just isn't that much active collaboration on the same trees (where people work together on the same tree on an ongoing basis)?
Regards,
Mike
Bronner