You need to also redirect all documents, desktop folder etc because it wont copy the files to your roaming profile on log off. This means say for example I place a new bitmap on the desktop and logged off and logged back on the bitmap will have been deleted. Another good space saving technique!
The only other slightly annoying thing for the end user may be the inability of saving favourites as they would be deleted upon logoff. As would the user account history, cookies etc. So if you were to use things you might want to find other ways of tracking their activities (especially internet).
If you have a lot of software this may mean that the ntuser.dat file increases to store the different settings for each of them and using this method may reset them each time. For example if a program runs a wizard the first time it is ran and was not run when making the default roaming user profile then the program would repeatedly ask you to complete this wizard the first time the user uses this program on each log on. e.g. without logging off the wizard can be run once and the program used repeatedly without the wizard running again. However as soon as the user loggs off and tries to run the program again the wizard would run again.
It may cause more trouble then it is worth but if you cant increase the profile limit then it may be worth considering especially if security is a concern.