Sorry, but no!
No, it is NOT acceptable where users are going to need to do lots of small edits, particularly if the user technically not very minded (and can't see the scale of the problem!)
This may not be possible with CloudMe technology, however from the user perspective I think what we need is "Soft Locking" - due to system lags there would inevitably be situations where conflicts occur. I think users will have to live with this. But the current situation with CloudMe (and the mighty DropBox) of having no protection from over-writing is disastrous.
From a user perspective here is how I would do it:
1. CloudMe needs to allow someone to check a file out - much like taking a book out of the library - and to KEEP it checked out even if they then go off-line. I think that is the main thing that is needed.
2. And if you start editing a file while you are currently off-line:
A) This should be possible although you should first be warned that it can not soft-lock that file,
B) as soon as you then become online, the system should attempt to soft-lock that file and it should tell you either way. And before soft-locking it should check to see if the file has been changed (or soft-locked) by anyone since your original copy was taken.
C) If you are off-line and start editing an (un-soft-locked), then as soon as you come back on line, if someone has edited your file while you were off line, you should be told immediately and the system should suggest a new temporary (conflict-type) filename to save with.
AND when the client has user-focus it needs to poll the central database occasionally to see if the other person has now saved/unlocked that file, and as soon as that is detected, the system should again fire up and suggest you open both files to see which changes you want to incorporate.
D) To stop users from hogging a file, whilst you have got a file soft-locked, you need to be reminded about this visually and prompted to let go of it as soon as you go on-line again. Ideally it would be have like a reminder in Outlook i.e. the user should be asked how soon they want to be reminded again. (say 10 mins, 30min, 1 hour, 0.5 day, 1 day etc) AND other users should be able to see how long you seem to have booked the file editing for.
E) Ideally you could even build in some kind of instant messaging system (with an user-editable in real time message if possible) so that we can messsage each other - Something like "Hi Fred - have you finished editing this file? If not how long will you be?"
F) If I was a betting man I'd say that in 5-10 years
i) not only will all this be free and easy (probably with only some of us paying and that would be either for the more advanced features or advertising removal costing anything - i.e. 'Freemium' business model)
ii) For security/privacy reasons we wont be using The Cloud as such, we'll be using Torrents to share across all our devices.
DropBox now has over 200 Million users, but they do not offer any form of assistance for 'collaboration' (e.g. as described above). All they do is "file replication".
However most of the world need to work collaboratively at least some of the time. And whoever cracks this problem first with an easy-to-use, intuitive interface will absolutely clean up!
What I can tell you 100% for sure, is that a number of your competitors are already working on this problem (e.g. copy.com and TeamDrive.com).
Whatever is done needs to allow for the fact that
A) most of us are not online continually. AND
B) we need to be able to work on - and certainly read them (if not edit them - although that will of course risk conflicts) even when we are off-line (e.g. when we are travelling).
Trying to help