I started out on Citrix in a multi - user environment with both the front and back ends on the citrix server. Am now using just Terminal Services on a 2003 server using Access 2000. The migration was esentially trouble free with the exception of printer management on remote (VPN) users and to solve this I had to write some code to set the printer (seems CITRIX is better at handling printing that TS is presently, at least for remote clients).
Of course I have the data bases split with a front/back end.
The users on the network merely execute a common front end that resides on the '03 server which is linked to the back - end database which resides on the same server.
No problems whatsoever (not a single database crash, not a single corruption, nothing) over the last 5 years with multiple users, even for users at a remote site that access the front end via VPN.
In addition, the applications are very fast, in fact, they rip.
For development, I have a duplicate of the front end/back end on the same server.
The only issue, from a multi-user perspective, that I have run into is record locking. One was related to the service pack level I was initially running and the other I solved with some code that tends to the issue that I gleaned from somewhere on the internet and it works flawlessly.
In this day and age, where you've got large numbers of users, it seems to me that, given the sophistication of Terminal Services, it's beyond me why anyone would choose to maintain front ends on every workstation when all you need is one copy on the server.